What is it about making promises?

I've just heard from a Christian guy I know through a forum that his wife wants to try a separation. While there are reasons for this that are obviously complex, all the evidence I have is that he both was and is determined to be good for her and still loves her very much.

Don't people make promises when they get married these days? Like "in sickness and in health, 'till death us do part'" or similar.

Or maybe there are new vows that can be taken, along the lines of "as long as your bank balance holds out" or "as long as your skin is smooth and your breasts firm".

It seems weird to me that you can promise one thing, but as soon as there's an issue then it's OK to renege. After more than 24 years of being married, I KNOW there are times when you'll drive each other nuts, but what were your promises worth if they can't keep you together through that. I'm not talking about domestic violence or infidelity here, but the sort of strain that is normal at times in any marriage. How is it that promises have so little value - or we walk with so little integrity - now?

I'm not sniping at anyone in particular in this. I know BOTH sides of a marriage have to want it to work before it can. I just don't get why they won't. Let me say that I do honour and respect those that DO stay together through their differences and difficulties.