I know how you feel, Except I don't think that there might be someone else, Although I wish there was , because then I wouldn't feel like its me. Read my post-My boyfriend hardly wants to have sex anymore.
I always thought that all guys thought about was sex, Boy is this guy proving me wrong, He makes me feel unwanted sexually and when I try and talk to him about it He gets mad. It's so hard to live with someone and sleep in the same bed and not be intimate and when it does happen which is maybe 2 times a month if I'm lucky, It lasts 3 or 4 thrusts and then its over. I don't want to leave him, but I need to feel wanted sexually, I just don't understand. I feel for you, because I know the pain your going thru. I have never experienced this in any other relationship that I've been in.
We live together , have a dog and plan on getting married too. But do you and I want to marry into a non- satisfying relationship???? Thats my dilemma and seems to be yours also. Keep me posted and let me know how your situation works out.