While I agree with you, to me, this is a sad outlook. If that's the case, which it always comes back to, there's not much reason for a guy to actually comitt to such a thing in today's modern climate. If the long arm of the law can separate you from half of your resources simply because you created another human being with someone, it's a caustic climate for a man to have kids in. If it was a "you pay half, I pay half. you don't get half my crap simply because I married you" type of situation, then marriage is worth considering. Women get lazy, entitled and see sex as a chore. I don't even want to have sex with someone who sees it as a chore but the horniness level is too tempting sometimes to resist.I think the basic difference is that for the woman, sex either is a chore or degenerates into one. That's the unspoken, but underlying implication I got from sazc's posts before she started agreeing somewhat with you guys. So sex doesn't cause enjoyment and stress relief, it just further causes resentment and discontent. It's another chore she knows she has to do to keep it together (or in cases like with your wife, knows she doesn't have to do). If sex was something she wanted to have because it makes her feel better and brings her closer to you to work out the relationship, then sex would have been part of the solution to the problems... not be the problem.
And this is more speculation, but maybe it comes back to the reasons why each gender is likelier to commit. Women can have sex whenever they want, they've probably had much more of it than you have, and probably with hotter guys than you. When she commits, it's primarily because you can provide her with some tangible object or individual, rather than reciprocal, emotion - kids, money, security. Men may be more likely to commit because they want good sex and bonding in of themselves. Again, this is just in general and speculation though. I am also tempted to simply say that dumb, selfish and crazy people create dumb, selfish and crazy relationships... but in cases where that doesn't apply, the rest may.