Sounds to me like you're a classic 'Bridge Woman'. I met author RM Johnson a few weeks ago and we were discussing this very same topic. Here's an excerpt from his site WHYMENFEARMARRIAGE.COM:
"Just around the corner syndrome," it is referred to by some, is when a man postpones marriage in hopes of finding his "perfect" bride. It doesn't mean he doesn't love the woman he's with, and it doesn't mean he can't see marrying her one day, if "it" comes to that. "It" being the day he believes other women are no longer attracted to him, or the day he finally realizes there will always be different women that may come around, but that doesn't mean they are necessarily better. But do you really want to wait that long?
Just how would you know if your man has "just around the corner syndrome"? One way is obvious. If you love him, and you know he loves you, if you have no major issues in your relationship, if most everything is picture-book perfect, yet there is some random reason he won't disclose why he won't marry you, your man might be infected with the syndrome.
Is there a cure? There is, but nothing you can administer. He will have to cure himself. The way that's done? Like I said, by him coming to the conclusion that you are, indeed, the woman that he has been looking for. He just didn't know it. Once that happens, you'll get that proposal. But till then, is there something you can do to speed this process?
We believe so. When it comes to the proposition of marriage, we at WMFM.com believe in being direct. If you're approaching thirty, or older, and you've been dating your guy for over three years, (and he knows he's the guy you want to marry) then you should find out what's really going on.
We aren't saying chase the guy, badger him, try to convince him to propose. To be honest, women should never have to think about telling her man she wants marriage. It has always been the man's place to court the woman, to ask for her hand. But sadly, those days are gone.
With that said, be direct. "You know, we've been dating for three years. You're living in my house, you say you love me, but every time I mention marriage, you make a face, and say you gotta go to the bathroom. What's up?"
Find out what the real reason for his procrastination is (if it's not the syndrome). If you're satisfied with it, and you feel he's worth waiting for a little longer, then set a new date in your mind, and don't bring it up again till then. If you think his explanation is nothing but babble caused by symptoms of his illness. "Uh, babe. It's just not a good time. I always told myself I'd be engaged for five years before I agreed to get married. We still have two years to go." Dump him and find someone serious about the prospect of being with you.
If you've been with a man for five years or longer, and he hasn't seriously talked to you about marriage, it's because he has no plans on marrying you.
Good luck to you and your children. Only you can make the best decision.