Why Won't He?

Side 1 says... So, I've been dating my boyfriend for four and a half years and we've know each other for seven years. We have lived together for a year and a half and get a long so great. Two Decembers ago, he took me ring shopping. He brought up the subject and asked me if I wanted to look at rings. I got to try them on and see how sparkly they were on my finger and I started getting really excited wondering when he would pop the question. It's been two years since this an dhe still has not asked. The subject has come up a few times since and he seems to shut down when it came up and just says he's not ready. He says he does want to get married and start a family though. We almost bought a house together this Summer when our lease was up and I told him I did not want to enter such a commitment without at least being engaged and so we decided to sign a lease for another year after him telling me again he's not ready. After this happened, I debated leaving him and getting on with my life. I'm 26 and he's 28, which isn't old, but after all that has happened and how long we've been together, I figured he would know and be ready by now. After discussing this with my mom and a few friends, I decided to stick around and just not mention the "m" word until this Summer when out lease is up again and when we had originally planned on buying a house, and then say "hey, either we need to get married or I leave." We have an amazing relationship besides the fact that I'm confused about his feelings on marrying me and I don't want to loose him. My main question is, am I stupid for sticking around and giving it this much time? I know that this may seem silly to people who think marriage is over-rated, but it's important to me and I know he does want to get married and have a family eventually. What do I do?!