He is deleting because he feels guilty. 

I'm sorry to say, I don't think that behavior is normal. 

I think he may have misinformed ideas about what higher T could do for him. 

I cannot imagine that a doctor would prescribe TRT for a man whose T levels are normal. It isn't without considerable risks (stroke, heart attack, etc ).

I'd definitely want to know why he wants to take more hormones...

I'd straight up confront him. "Why are you texting other women- then deleting those texts? Yes, I went through your phone because I thought something might be up. Clearly I was right so my going through your phone is NOT the issue- your going outside of our marriage for attention, is. So, care to explain?" 

Guys try to flip it. The problem isn't you going through his phone- the problem is you not trusting him and him prooving you right. 

My DH's text exchanges with females are mostly with his mother. Occasionally he texts with my mother or BM (related to skids). He does have one long-term female friend who lives OOS and with whom he has a brother-sister type relationship who he communicates with fairly often, but more on SM than text. He doesn't have many female co-workers, certainly none he sees for more than a passing minute in the office (he's in the trades and mostly out at jobsites). So to me your SO's texting with women doesn't seem normal.

Have you asked him why he wants to take testosterone? That seems odd if his is normal.

Putting aside the phone for a minute, let's look at the cause, not the symptoms.  He says he deserves to feel his best, so what part of his best is missing? Is it something physical that he hasn't shared with you (or that the doctor doesn't deem significant?).  Is it mental? Is he fighting ageing (women aren't the only ones who look in the mirror and hate the weight, the wrinkles and the sag).  Perhaps he's feeling like he's losing his edge and that testosterone will help him bulk up, lose the age related weight and make him the teenager (or 20 year old) he sees in his mind rather than the attractive man you see when you look at him.

Perhaps a discussion of WHAT he's trying to accomplish with his sudden interest in amphetamines and testosterone.  I know if my DH came to me with the thought that he'd be starting on a pill regiment for any reason I'd want to know why, what he hoped to get out of it, and what the risks were (getting them illegally would be a risk too far!).  And if I could empathsize with his struggle, I'd support it (legally).  If not, I'd make sure he know how attractive I think he still is, ask if my ageing bothers him as much as his, and if he's being realistic.  If it's an emotional problem I'd lay it on the line that this is the type of thinking that leads men to look for more and more attention until they find the person willing to stroke their ego and kill their marriage.  That eventually everyone gets old, and he's not some Hugh Hefner with millions of dollars to pay some 20 something year old girl to so she'll pretend he's hot.  He's a great guy with a great woman, who still finds him attractive and he's having regular, quality sex.  So he needs to get his emotions sorted out before he screws that up for the third time!

1.  It's not normal for most men to have daily texting conversations with women who are not related to them .  

     I would consider my DH is on the high end of being a communicator for a man.  He has multiple texts or calls with any number of people daily.. including ME.. his daughters.. his father.. MY father.. and other male friends.  My husband does not have many "non-related" females in his phone.. the few he has are not in his heavy rotation of communication.. just acquaintances on the outer rim of our universe..   He does have some women that work at his place of business.. but no business need for them to communicate.

That is the only small slice of possibility is that if he does have to communicate directly to cover shifts.. perhaps.. and being "nice" is not  the end of the world.. but I don't use winky emojis when I am asking my coworkers a favor.. lol.

2.  Re the Low T thing.. does he listen to a lot of talk radio where they harp on those commercials.. "low t"?  Is he particularly gullible to claims of things "changing your life?"

   Otherwise.. big changes or wanting to make big changes in appearance.. ability.. etc.. seems to point towards someone that is seeking out something or someone new.  wanting to look or be their best for that unknown.. because certainly.. you have told him you find him more than adequate I'm sure.

3.  Deleting emails.. especially in a focused way is not normal.  I could see freeing up space on a device by deleting en mass with perhaps some things retained.. but just women? uh.. that seems suspect.  

4.  2x prior cheater?  It's almost the nail in the coffin to the likelihood that this is all an innocent misunderstanding.

Not saying this is the case for you, but I knew my first marriage was over the day I checked my ex's phone. I realized that even if I didn't finf anything, he had behaved in ways that made me question him. We were together for 18 years previously and I had never felt the need to check up on him. 
 

ETA: the next time you get your hands on his phone, check hist snapchat. If he doesn't have an icon on his screen, check his settings to see if he has it. Apparently, using snapchat instead of rextbis cheating 101. 

Don't try to logic yourself into wasted years with him. Trust your gut. Use the facts about past behaviors.  Use the new info you have about him.   What would you tell your best friend or sister?   Acknowledge the red flags.  

Husband is a mechanic that does side jobs. Women text him about their cars, but he has no ex gf or "women friends" that he back and forths with.

Emotional cheating is still cheating. Texting is dancing the lines.

Listen to your instincts.

BUT HELL TO THE NO IS THIS OK...I work with all men and have for the last 30 years....I do not text them other for work issues, etc. I might talk a bit to my co-workers but they are that CO-WORKERS.  No need for me to text them after hours, at home.  The fact he is deleting them shows HE KNOWS IT ISN'T OK.  

He doesn't need more attention than "normal" ..HE NEEDS THERAPY.  

Ah..so ya my DH (in this instance dick head husband) thought that texting other women wasn't cheating and it was "seperate" from our marriage.  KNow what..it was cheating and it certainly wasn't seperate. It about destroyed his marriage, his relationship with his daughter.  Dh too thought..he "needed" the attention since I was so busy. Yea..I was busy running our lives and taking care of his kids.  He didn't "need" more attention he needed to get his head out of his ass..step up and help me out and support me.  Once he realized and started that..magically our relationship got better..that and I wasn't sharing a marriage with hundreds (yes hundreds) of other women.  Oh and let me add this...during the years DH was texting every whore known to man...he also was working out and wanted testostorone, etc.   I thought it was weird..but now I know why.

I'm going to be blunt..until your SO gets some serious therapy..he will continue to do this.  He will seek out superficial "relationships" with other women..cause it makes him feel good.  Your SO needs to find out why he is driven to this..and until he does..he will be a shitty partner for anyone.

Is this bothers you. So yes its an issue.

Frankly this would bother anyone who wants a monogamous relationship.

This doesnt pass the smell test.

Stay living apart until tommy texter puts proper boundaries on all his lady friends. Add to being the texting deleter, not kewl.

Im a pessimist so I see this as an ongoing problem. He cheated in the past, chances are texting may be the least of your problemos hun.

I didn't read everyone's responses but this is my opinion. I talk to a male ex co worker (still same company but not together) of mine almost everyday. He's 20 years older then me... has also  know me since I was 19/20... im 37 now. SO knows him, we all go out etc. Another couple we are close with is someone (husband) Ive met at work who are in their early 50s too. I communicate with both but mainly the husband for plans. It's just how it is.. We vacation with them we are that close. 

I've also been in multiple group texts with all males that I've worked with.. this chat goes everyday. SO knows everyone in it. Variety of ages... and I show him half the stuff anyways. It's all fun.

SO is more "quite" when it comes to his female co workers but he doesn't interact with people like I do for work. 

Every situation is different. SO has never shown any jealous because there is legit no reason for him too.

In your case... I think your SO is just headed down a path of wanting to be young again and this Britney chick is bad news.

My SO has talked about going on TRT. He is 46 he doesn't need it now but he will at one point. He is a work out type etc. SO deletes random stuff out of his phone too. Mine I have texted from years ago still in here haha.

I think your SO is down a dark path IMO. I'm sorry this is happening.

EDIT: none of my convos are flirty to and receiving. It's a lot of work drama, ball breaking or all of us talking crap.

So what ever drugs she is on is ok I guest I don't have a MD can't comment on drugs.   But more importantly is your life with a sick SD.  You didn't signed up for this. You don't have to stay 

I had a gut instinct with my exH, and boy was it correct. Yes, I did check his phone after he got verrrrrry protective of it. One night he basically passed out (oh, alcohol and drugs too - fun times) I checked it an yep, there it was. He denied it to high h*ll over and over, but even IF they weren't sleeping together the sexual innuendo and meeting up when I was at work (sometimes right after I'd leave for work and she'd "leave the door open for him"), yeah, no. Then he locked his phone down and forgot about his laptop which he had moved to his dresser instead of the shared office. Idiot.

Testosterone!  My DH is on that as well, just a small dose. When he was diagnosed with ADD years ago, he was also diagnosed with low testosterone. If he doesn't take it, it dips super low and boy, he's annoying. BUT if he takes too much - watch out. He was on too high of a dose for a while and he was mean, argumentative, dismissive and just plain horrible. I was considering possibly leaving if it continued. He finally figured out something was wrong, got a lower dose and has not had an issue since. So no, it's not a little thing to do, esp. on top of ADD meds.

Did your SO do therapy or otherwise work on himself after his first two marriage ended with him cheating? Did he try to figure out what in him was broken that he'd dishonor his vows and cheat? If not, I doubt he's changed. It may just be a matter of time before the desire or opportunity presents itself.  The more women he's texting, the more opportunity to go over the line.  Regardless of what other men do (and I answered your question above with what my H does), I'd be very concerned in your situation. 

Ugh I'm so sorry. I hate this for you. Regardless if he is crossing a line or not by society's standards, what he's doing is bothering you and that's not ok. I hate it when my DH's crazy ex bothers him (and he doesn't text her back that I know of but it still upset me). I would be upset by what your SO is doing. 

He is a jerk. Time to move on. I am sorry but there is no way you should stay wuth this man another day

This situation simply continues to spiral. Get out before it gets even worse. He is not a quality man in many ways and you deserve to be matched with someone much better than this. 

Although I don't know the dynamics of your relationship, this puts up a lot of red flags to me. My DH and I are roughly the same ages as you and your's, and the behaviours your SO is exhibiting are similar to my ex boyfriend from almost 20 years ago. Juvenile, emotionally stunted and attention seeking actions. It's not something I would put up with at my age now.

Edit: My ex was schtupping any woman who paid enough attention to him at the end of our relationship, and he also deleted texts and spent time "networking" at parties and bars. 

the moment is not normal.

IMHO, it is just the never ending avoidance of personal accountability.

If stupidity can be blamed on some syndrome, it is an excuse to keep doing stupid shit.

meh

IMHO of course.