I'm not engaged, but I have been with my boyfriend for nearly 9 years. I'm just not interested in marriage. He asked me once, and I said, "Why?" He wrote Marry Me on the bathroom mirror in the steam while I was in the shower. I didn't even notice. Later he asked me about it, and I told him I don't see the point of weddings and marriage. Two people can be totally happy and committed without marriage. It's just a strange concept to me.
My friend is in your boat. She has been dating her boyfriend for 2 years. They haven't even talked about marriage because she's afraid to mention it and scare him away, and he hasn't brought it up at all. She was looking for a husband when she found him on a dating website. She is itching for a ring so bad, and it is driving her crazy. I always tell her to just tell him how she feels. I tell her that if he is truly the one, then she should be able to tell him anything, and it's better to tell him now and find out how he feels than still be wondering where she stands in 5 years.