Boyfriend keeps reminding me of when we didn't have sex. I was the one that wasn't interested. He talks about it for two weeks. How do I respond. We are only friends, and I don't feel it is my obligation when I am don't feel like sex?

Sex drive for men, are usually more visual based, versus most women  being based on touch. Once a man fixates on sex, they usually have a difficult time concentrating on anything else. The sex drive for both sexes are governed by the certain hormones levels in our bodies depending on our diet, exercise and usual natural flow regardless of there being too much or too little of it.

Unfortunately, it is the way our species is designed . . . The problem with this is that a lot of times monogamous partners find themselves out of sync.  Tell your boyfriend/friend, that if he feels the needs so greatly, he can have some "Private Time" to take care of this himself. This is perfectly natural and should not be viewed as negative by EITHER party.

I'm confused too, is he your boyfiend or friend?  If he is a friend that you are just having sex with then that's why he is talking about it. This is the problem when people use each other for sex.