Same thing happens to me but it only takes 1 or 2 months to get tired of them. Even if the sex is good, I want to have other pussy on standby. Sometimes I wish i could change because I just lost a girl and now I wish I had her. It sucks at times when you hear of other people being with the same chick for a long ass time and you can't seem to settle down. I'm 25 now and all my life I've been with multiple partners but I want to change my ways. I've tried many times before but always failed. I think I'm just going to buy a blow up doll.