I have been with my girlfriend for 6 years. She's really attractive, intelligent and funny. However a few months ago I stopped enjoying sex with her. Last night we were kissing (at her instigation) and I felt absolutely zero, nothing, not a stir. In fact I felt slight revulsion and claustrophobia. This is a woman I loved so much and enjoyed making love with and gladly gave up a LOT of things for.

We don't live together, she has kids and other lifestyle issues which collide with mine. We see each other 4 or 5 times per week. She is prone to melancholia and dark thoughts and is somewhat neurotic by nature. I don't see any future for us living together actually.

One other problem - she loves me to perform cunnilingus on her but will not 'go all the way' when fellating me, which in turn leaves me feeling very frustrated because it's something I really want, to the point of need: she says it would make her vomit (actually she did it twice in the past six years and she didn't vomit). She says she's had the best sex of her life with me and I helped her become a much freer person.

Anyway ... what happened to me? We haven't had sex for more than a month - she wants it badly but I absolutely do not. I still feel normal levels of sexual energy and strength though, e.g. I masturbate every couple of days or so, but the thought of making love with her leaves me worse than cold.

Any suggestions?