Why do I lose sexual interest in my GF's

Go see a shrink.

+1

+1. A little of this is normal, but not to the degree you're speaking about. You also sound sort of immature and maybe somewhat shallow. Part of your problem may be that you are not making anything beyond a physical connection with the girls you're dating-- try having a deeper relationship with people (read: search for more than looks).

just do it anyway, then it will come back to you

Another vote to see a shrink.

This may come off as a joke but it sounds like you don't like girls. Assuming you are a young man (under 30), not wanting to have sex with girls has to be the greatest indicator of your sexuality. Now if you are a much older guy and you've been with tons of women, I can sort of see where you want companionship more than sex but if you are dating a girl and worried about having sex, that's just wrong on many levels.

Do you like, literally, only have sex with them once and then lose interest? Do you develop some kind of anxiety about having sex with them more than once, or do they simply fail to excite you?

Well then see a shrink- it's probably a deeper problem.

Maybe you should just continue being a slut, since you mention that you can only achieve satisfaction from the first sexual encounter. I think subconsciously, you're telling yourself, "I'm young, I don't want to be tied down, I'd rather dick around forever, and never have to meet 59." I think you might have trouble disassociating 'commitment' from being 'old' which might be what turns you off from developing a relationship with the same person.

Wow. Shrink, cut out the porn. See what happens. It can only help.

You lose interest in women you have been with for some time - an absolutely shocking and unprecedented condition for a young man.

He just seems to have an exaggerated version of the intense desire for one lover, clashing with the desire for variety, which is the basis for so many tragedies and comedies and is so fundamental to the our sorry but fascinating human condition.

You must be right to raise the issue of pornography as its recent prevelance adds a new and twisted ingredient into the old, frustrating, mixture. We can analyze to death what pornography does to us. For better or worse, it is certainly an addiction and apparetly it has increased rates of masturbation, which in turn diminish desire for actual women.

Ah, and then the tired "examine your sexuality" comments. Our society is rather hung-up on this thing, aren't it?

And here come the predictable "go see a shrink" responses, as if the state this fellow describes reveals some kind of incomprehensible dysfunction. Every slight abnormality must be treated with psychological analysis and probably drugs. Believe me, every morning I feel a million different anxieties and wonder why there isn't just something I can swallow that will make them all go away. Do I find the late twenties frustrating and depressing? Absolutely. Have I given up and accepted that life will be miserable? Yes and you can too. It is the first step. Strangely, I think it helps with commitment. If you recognize how maddening and terrible it is to be human, you might be more tolerant of your partners. Or maybe not. Just give up on solutions and relax. There is probably no satisfactory answer.

We have shrinks because we can't always talk to family members oe friends who are far away or caught up in their own problems. Besides, they come to the problem with their own interests in mind; the shrink is supposed to be some kind of unbiased observer.

Maybe you just are this way...but we need solutions and the same happiness that our peers and people on TV seem to be enjoying. We have an undying craving for normalcy.

Maybe you should forget about the sex and focus on one part of the body of your lovers.

My amateur 2-cents analysis.

I guess the question would be how much do you actually respect women? The comments about pursuing and bedding women and having more sex than most people your age suggest to me that you treat women as objects to be attained as sexual trophies, not so much as people with whom you want to pursue a real relationship.

I'd suggest putting off the sex for a while in your future dating and building a relationship based on something other than physical attraction. That way the sex is an added benefit, not the entire basis of the relationship.