It sounds to me like you're ready to go but you feel you'd be letting her down if you do. Here's the thing, if you do stay, just so you don't let her down, you still will. You'll let her down because you can't give her the kind of two-way happiness she wants. You'll be miserable, and that will make her miserable. Before long you'll end up trapped in a loveless marriage because neither of you wants to hurt the other. If I am reading this right, the best way to avoid, or in this case minimise, any hurt, is to end things as soon as possible. You're both still young enough to have true happiness, raise families etc.

I may be wrong, you could be just in a rut. When was the last time you went out together, just the two of you for a romantic evening (dinner etc)? When was the last time you spent quality time together just cuddled up on the couch? If you are in a rut you can save this, and I hope this is the case.

I'm 36, not a lot older than you, and before I married my ex wife at 31 I felt much the same. We split after less than three years because we were both miserable. If the problems are worse than just being in a rut, marriage won't solve them. Any problems you have no, if not resolved, will continue into the marriage. If one of you isn't 100% in, the marriage won't last.

The upside though? A couple of years on from leaving, I'm happier than I've ever been. I've a new, fantastic lady, a new job and everything is coming up Millhouse. As for my ex, she's still single (a couple of guys were around for a little but didn't last) but she appears to be happier than I've ever seen her. Sometimes, you just have to cut your losses.