Me and my boyfriend have have sex and pleasured each other so many times and I used to orgasm every time, but lately I've found it difficult during sex and it takes longer to get there when he's pleasuring me. The sex is an average time, but not enough for me to reach that climax. And during him pleasuring me, it feels great and I almost orgasm and I tell him to stop cause I've reached my climax but then suddenly it goes away and I didn't orgasm like I have before. Tips?