This theme - can anything break marriage vows? - keeps recurring in this forum and I'd like to hear people's thoughts on it.

People often bring up the "for better or for worse, through sickness and health, 'till death do us part" section of marriage vows and they quote them as a justification why a person must never leave their mentally-ill spouse, no matter what.

For many long, long years, I struggled with that "moral catch-22". That is, I felt that to leave my bipolar wife would be to abandon her, and that I had a moral obligation to her because of my marriage vows. And while I struggled and maintained the status quo, my life and my health went downhill.

After years of this, I finally understood that it's neither healthy for both partners, nor is it realistic or practical. Do those vows mean that you stay even if you do irreperable damage to yourself? Even if it destroys your own mental and physical health? Even if, because of your own deterioration, it creates an environment in which your mentally-ill spouse gets worse rather than better?

Besides which, the "never leave" marriage vow is broken all the time. Your wife, a teacher, was just convicted of statutory rape for having a two-year sexual affair with her 14-year-old student? Your physically abusive husband just shoved you down a flight of stairs and broke your collarbone for the sixth time? In cases like these, the "never leave" vow is voided with the blessing of both society and, in many cases, religion.

I finally came to... well, I was going to say "a realization", but it was more like I decided to acknowledge something that I knew was true but felt wrong nonetheless:

A marriage certificate is absolutely not a "get out of jail free" card.

For me, my wife's willful self-destruction, her abusive actions towards myself and my kids, and her refusal to help herself even though she knew she was ill and she was hurting the people around her, violated our wedding vows. As such, I knew that if it came to that point I could leave her and have no moral or ethical qualms about it.

So what about everyone else? In your opinion, is a marriage truly "till death do us part"?