Let me preface this by telling you first, that I am a 20 year old male. I Identify as straight and am sexually and romantically attracted to women. I also have an extreme obsession with the idea of receiving anal sex from an older man. It dominates my sex life, and it makes having sex with my girlfriend very difficult, and she thinks that I am not attracted to her. I don't know why I have this fantasy, but I have thought a lot about this and remember a few key memories in my sexual development. When I was younger (say 11-12 years old) I would sneak into my mothers room when she was out and dress up in her underwear and lingerie. I would also experiment with her tampons by trying to "use" them. This progressed as I got older and by the time I was 13-14 years old, I had found my own mother's sex toys and used them to pleasure myself. On top of that, I also found sexually explicit pictures and videos of my parents having sex. Normal sex, but nonetheless I found myself coming back every time I was home alone.I grew out of that phase but around 15-16 years old and up till now, I have had an unhealthy preference for "Shemale" Porn, specifically fantasizing about myself as the transgender person and only on the "receiving" end. Around the age of 18, I also began to fantasize about having anal sex with an older man. I would put craigslist ads out looking for people, and I ashamedly did actually work up the nerve to do it once. I didn't really enjoy it yet I still fantasize about sex with an older man.
I have been haunted by this for a while now and am trying to figure out where this came from and how I can overcome it. I would love to pinpoint what exactly caused my obsession. Thanks in advance.