I downvoted you for your bias about marriage vows being meaningless in a non-religous context.
It may be difficult for the religious to understand, but atheists and agnostics can certainly be as moral or more so as a religious person. Those of us that are not religious can derive our morality from valid sources other than religion, including real life. Humans do not require morality from a higher power, and to assert otherwise is to assert your own bigotry.
That's fair, but I just don't see why anyone would allow a "vow" to have any hold on them in extreme situations unless they felt some cosmic thing were being violated. There is certainly no legal or even significant social pressure to stay with a spouse at any cost, so what significance does breaking the "vow" hold? Not being true to oneself? Then you're sort of your own god, willing to punish yourself for something everyone else is readily willing to forgive you for.
I can't imagine someone making a personal vow to pay back their mortgage at any cost, when they're legally allowed to walk away. Even if it meant the total destruction of their future.
It may be difficult for the religious to understand, but atheists and agnostics can certainly be as moral or more so as a religious person. Those of us that are not religious can derive our morality from valid sources other than religion, including real life. Humans do not require morality from a higher power, and to assert otherwise is to assert your own bigotry.