Should I stay with my boyfriend?

I have been with my b/f for 6 years, since I was 17. He was my 1st real boyfriend, and is 10 years older than me. But now I am not sure whether I am still in love with him. I love him, and he is like my best friend, but I am not sure he is "the one". Is this just how a relationship gets, or should I expect more? I am scared I am just settling becaause it is the easy option. Advice please.

Update: July 03, 2009.
Just some added info: I don't feel attracted to him anymore, I never want sex, but I don't feel very attractive myself as I have put on weight, so maybe thats my problem. We basically lead 2 lives, we are both independant, which is good, but he has to make all the decsions, even silly things like if we go out, if I suggest somewhere, he suggests somewhere else and we have to go there. If I disagree with his opinion, hes the one who has to be right. I don't know whether I am just being picky, I just don't know!!! aarrhhh