Just because this is the best relationship you've ever had doesn't mean you have to stay. If you feel like there is something lacking or that you cannot communicate with him, then remember who is your number one priority: You.

What have you talked to him about and how have those conversations gone? And my personal rule of thumb when it comes to sex is that if you can't talk about it, you shouldn't be having it. Relationships takes a lot of communication (and thus a lot of work on communicating...), so I would start there, with conversations that begin with I statements -- "I feel..." "I don't like..." "When you do .... I feel .... "

Good luck!