I am a female and my boyfriend have been dating for three years and we are both 20 years old. In the beginning of our relationship we used to have sex at least 5 times a week and it was very spontanious, but that changed to about once a week and very routine. Lately I just have not been wanting to have sex at all and I don't know why. I mean it's not him at all. I think he is super attractive and I think about having sex with him, but when it comes to the time I just don't have those feelings. He often makes the move, but sometimes I will just say I'm too tired or say we'll do it later. We have a perfect relationship and everything is just fine it's just the sex. I don't want him to cheat on me. What is wrong with me and what should I do?