When you're in a serious relationship, there is a general unspoken understanding that you will stand by the other person's side and help them through whatever comes their way, no matter what.
And if that relationship just happens to be a marriage...well, there's a good chance you made a vow to do that anyway.
But judging from today's AITA story, it would seem that not everyone is capable of fulfilling their half of the "for better or worse" bargain.