I’ve been married for over 20 years now, and there were times in our marriage when one and then the other of us was about ready to throw in the towel.
I think the thing that pulled us through in both cases was that the one who was less unhappy with the marriage really, deeply, honestly cared about the other’s happiness and made it clear that s/he was willing to do just about anything it took to get that back. I know that when I was going through it, I was unhappy not so much with my husband as with my life. I felt unfulfilled in my work, useless in the world, and utterly hopeless to change anything about it. My husband talked to me about that, even though he was going through the hurt and anger of my shutting him out, and he convinced me that he was truly willing to support me in any changes I needed to make. After I’d made some of those changes (I like how that phrase is so short and easy to say, considering how difficult it was to actually do), I realized that I wasn’t really unhappy with him or with our marriage. I had been unhappy with myself and that made it impossible for me to be fulfilled in anything else I did.
I don’t know what your circumstances are, or where you or your wife are in your lives. There often comes a time in people’s lives when they reassess where they are and what they’re doing and realize it’s just not enough. “Mid-life crisis” is too cliche a term to use, but you get the idea, I’m sure.
Divorce would hurt you, your wife, and your children. There’s no way around that. Every situation is different, and I mean no disrespect at all to those who are divorced and doing their best to provide everything their children need, but there is some evidence that even a somewhat unhappy intact marriage is indeed better for the children than two happier single parents. I would never advocate anyone live in a hellish marriage just to try to provide a “traditional” home for their children, but it might be worth living through some unhappiness now in the hope that things will improve in the long term. Divorce tends to be final, and you won’t be able to undo the effects of splitting things up if you regret it a year or two down the road.
As I said, I don’t know the context of your marriage. However, if you’re willing to keep on trying, and you sound like you are, you may have to give more than half to the marriage for a while, until your wife can recover the ability to give back. Individual therapy in addition to marriage therapy might be a good idea, and if you can convince her that you have her best interests in mind as well as your own, there’s still a chance you can come out of this stronger than before. If not, then you’ll know you did everything you could, even if it failed. I wish you and your wife all the luck in the world.