My BF and I have been together for about 2 and a half years, and I have known and cared for his daughter from his previous marriage for 2 years almost exactly. She is turning 5 in April, and I'm having trouble feeling as though I belong in the picture.

SD loves me and is a very sweet, sensitive and kindhearted girl, and we generally get along well. She tells me she loves me and I love her, and it's obvious that we have forged a true bond - as myself and her, only. When BF comes into the picture, it starts to become more difficult.