losing interest?

My boyfriend and I have been together for 3 months, it was all magical up until about last week. He was literally like a dream, after having a 5 yr abusive relationship I couldn't believe I found someone so great. . well.. lately he's been more quite, not to lovely, we used to have sex about 3 to 4 times a week and everynight I slept over, last night, he passed out within 5 mins of me being over and this morning barely said a word to me.. I don't know what to think. ALSO at dinner a few nights ago, he was checking out our waitresses.. even told me when one kept walking any how pretty she was... I didn't say anything cause I didn't want to start a problem but it really hurt my feelings, and it was like it was nothing to him. I'm so lost, I dint knoe what to do.