He doesn't want to have sex anymore.

My husband and I have been married 11 years and for the last 6 months or so he says he wants to get lucky but then when the time comes he just falls asleep...I love him very much and want to leave him but I don't know what to do anymore. I've tried to talk to him about it all hr says is that he is tired.. I feel like I just live him and we raise our kids but there is no passion anymore. It makes me feel like he isn't attracted to me. Any advice or words of encouragement would be greatly appreciated.