Just last year a had a relationship that was kind of similar to yours in the sense that I was extremely happy with my boyfriend and felt like I could be myself around him. In some ways, I felt very happy and the thought of transitioning was pushed far back into my mind; it almost didn't matter to me anymore... My entire life revolved around this guy. I became obsessed, and it wasn't healthy for me at all.
But eventually, I realized that I hated the way he treated me. It's not that he was rude, disrespectful or abusive, but that he treated me like a girl. I became afraid. I didn't like being treated as a sweet, fragile, dependent little girl, but I felt that if I tried to be more masculine, it would be off-putting to him, and he would leave me. Eventually the relationship ended for other reasons, but he was still constantly on my mind and still a part of my life. It wasn't until months later that I was finally "over" him, and my actual problems came back to bite me in the ass.
After finally getting over this guy, my dysphoria became apparent to me. Our relationship had lasted for over a year and a half, and during that time I was so desperate to please him that I was no longer cared about me. I was uncomfortable in the feminine clothes I owned, but I had been wearing them in order to be a pretty girlfriend... To please him. I know that sounds sick, but like I said, I became obsessed with our relationship. It was a welcome distraction from the depression I faced following my parents' divorce.
So I began exploring my own mind and my own needs, over the past several months I have come to discover some important things about myself... Things that brought me here to this forum. I suppose I don't really need to go into details, but I will share that I have a therapy session coming up very soon, and I am extremely happy about that...
Ultimately, the relationship I had with my ex affected my desire to transition because I couldn't think of anything but him. I was in love, but it was a dangerous, obsessive type of love.
Like Osiris said, take other people out of the picture. Focus on you. Find a counselor. Though your desire to transition may be affected by the people around you, in the end it is all about knowing who you are, and what you need to be happy with yourself.