No, it's not ok. You can't just "love" someone on demand. 

She needs therapy just as much as her son. It sounds like she is "overly mothering" him and causing him to be emotionally stunted. 

I would remind her that you have 2 children and they are being affected by her son.  She needs to "love" your children as much as you need to "love" hers and shield them from his "I want to kill myself and please pass the potatoes" crap at dinner.  Not just you extending yourself for her moody 14 year old who is just being what is currently fashionable for 14 year olds at the moment.  Both of you need to show care and concern for all of the children under you roof.  That is what passes for love in a step household unless and until the skid themselves decides to be lovable and form a real connection with the adult.  If - and that is a big if - that happens, it is either there from the beginning when the skid never knew anyone other than the step parent or develops after the dreaded teen years have passed.

Meanwhile, mommy needs to realize that the only other person who is going to love her mopey teen is his biological father.  She is lucky that she found a man willing to try to get along with him in exchange for her trying to get along with his soon to be hormonally hell on wheels teenage girls.  You have much to look forward to in the years to come.  May I suggest bourbon?

Sleeping in his room one night a week? what is that supposed to do? Either he is at high risk of suicide and needs the supervision or he isn't. I'm not sure I have heard of cases of depression that only get suicidal on Tuesday nights.

This therapist sounds a bit crazy. If I were you I would see if your wife will set up an appointment for you and her to go to see his therapist together (without the ss). Tell your wife it is so that you can better understand your ss and hear from the therapist their suggestions how to best suport him in your home while also caring for your own kids needs. Really go so that you can suss out if your wife is missinturpreting/lying about what this therapist is saying or if the therapist is crazy. 

If the therapist is crazy they you may be able to get your wife to use a different threapist for the boy if you are lucky. If your wife is lying then that is a whole other level of issues to deal with.

Judging by this site, very few step parents love their step kids, nor is it reasonable to expect it.  It is reasonable to expect that you treat them with consideration and civility, but that is a very different thing.  Your wife saying to you that if you don't love her son, you don't love her, is manipulative in the extreme.   She also needs to dump this weird therapist.   She needs to set some boundaries for this boy - it sounds as if she is so anxious and desperate about him that she is not setting any at all, and this won't help him.  Talking about suicide at the dinner table is unacceptable and also very manipulative - but he has probably learned this from his mother.  Don't allow either of them to manipulate you, is my advice. 

Sounds like some Bates motel stuff.

Don't end up in a hole in the backyard.

Even worse, imagine if this 14 year old boy starts looking at your 12 year old daughter.

I'm sure that the boy was used to basically having his home and his mom to himself.  12/14 (not sure which since you use both) is a tough age range anyway.. and lots of kids can feel lonely and left out by life if they aren't progressing at the same rate as their peers.

It sounds like mommy made the mistake of confusing closeness with codependence.  Now, you and your kids are the intruders.  He whispers to her because he isn't comfortable with you and your family in his home.  He doesn't see it as a shared home.. and it must be tight with three extra people in it now.

Now, I don't know what kind of jack leg therapist is encouraging a mother to sleep in her preteen boy's room.. that just sounds whacky.  It doesn't even sound right.  I mean, certainly there are other ways to show the boy that he is still an important part of her life?

And.. what you did to him about leaving when he wasn't ready.. was what my own parents would have done.  You got your shot mister.. and I am treating you just as I would my own kids if they were fooling around and not getting ready.  

It sounds like this is a situation that was rushed into.  Because I would have thought a lot of these things would have come up while you were dating and you and your kids were spending progressively more time with him and his mom.

is this a qualified therapist with a degree or did she barely pass her course?? 

Honestly i can say majority of teenage boys are wanting to be independent and with friends, not cuddle upto mummy yet alone sleep in same room as her... 

it feels current generation of kids haven’t got he memo to start growing the eff up and stop with the hissy fits. Look mental illness is real but alot of kids nowadays just claim depression because they haven’t been taught the necessary coping adjustment mechanisms

A Mama's Boy is a Mama's Boy because it meets MAMA'S needs, not because he necessarily wants it. It's called enmeshment, and the therapist is an idiot if she encouraged more of it by suggesting your wife sleep one night a week with a boy in puberty. It is exactly what you said - emotional incest. And again, it's to meet HER needs.  As you can see, it's damaging the boy.

As to her saying if you don't love her kids, you don't love her, that's the biggest bunch of BS I've ever heard (and further makes me worry that you have married an emotionally unhealthy woman).

Who is so screw up.  You Loving him is not going to fix anything?  First you invade his home made him feel second , because his mother has to divide her attention between you and him.  He never has a healthy relationship with his mother.   Why would a 14 yo want his mother sleeping in the same room.?  
There a lot going on here. 

smh

No one can force another to love anyone. Though you certainly can choose to love SS.  Though I completely understand from your OP that he is far from lovable.

I have a thoughtjudgement on  your bride though.  Her if you don't love him you don't love me crap lables her as an idiot.

You are doing exactly what this kid needs. Holding him accountable for his crap.  Leaving him behind as he dawdled around instead of getting ready for the men's breakfast is exactly what you should have done.

I would suggest that any time he pulls his attention seeking suicide talk at family meals that you tell him to leave the table if he can't interface with appropriate topics... or better yet, you and  your kids immediately get up and leave for a meal out leaving SS and DW to wallow in his manipulative crap.

I feel for your children and for you.  Selling your home and moving in may have have been premature.

Oh yah.  And the "mommy needs to sleep with him once a week" therapist is an idiot.  No more marital resources going to pay that idiot if I were you.

Good luck.