I think I can sympathize with you: I have experienced a very similar problem myself. Personally, I think that if you (partially or totally) unbond the idea of sexuality to that of love, you may have better chances to deal with this...
For instance, and given your picture (long live the old Gainax), consider the next ideas from Karekano: after finally having sex with Yukino and opening her heart to her, Arima, rather than being happy, starts feeling strange; at some point, he finally realizes why: now that he has finally touched and reached her, it is now evident and unavoidable that they are actually two persons: to reach someone else, rather than unite people, separates them; you might be able to go together with a lover, for a while; but to unite with her? to become one?... is it possible to have such thing with an actual someone (else)?
I mean: just take it into consideration, to arrive to your own conclusions; neither I have it very clear myself.