Bf doesn't want to get married?

I'm in a very happy relationship. We've been together for almost 2 years. I'm 26 and he's 30. I've been engaged once when I was 19 and he's been engaged twice. I started thinking about things and thought it was strange that he would want to marry these other girls that were totally unhealthy and wrong for him and not want to take that step with me. I asked him about it and he was just like "so you want to get married?" but he sounded kinda upset when he said it. I told him that I love him and I don't need that to be happy with him but. If he asked me I wouldn't say no. I asked him if there was something wrong with me or if he doesn't want to end up with me. He said it's not like that and both his prior engagement the girls asked him. I'm not going to ask him- I refuse to force that on him. I know his last relationships ended badly so I can see how he would be wary of it. But I would be lying to myself if I said that I don't want to get married - I don't want to end up being 40 with a bf. Not that I can complain if we are happy and love eachother. But I'd like to finalize things with him. I love him and want to make him happy. I'm s ares to bring it up again since I don't want to make him feel cornered. Should I keep quiet for a while or let him know that I want this. I want him to want it too though. I woulnt want him to ask me just to appease me.