In my case, it was not implicit; it was explicit ("Til death.") Besides, Catholics have classes to take beforehand which are supposed to explain what the vows are about in the context of married love. Our classes weren't much, in my opinion, but at least they conveyed a couple of key concepts like "exclusive," "faithful," "open to life," and "permanent."
You wrote: "I think as a practical matter, one spouse saying 'Get lost' is all it takes (and that does not necessaily have anything to do with the As you mention). How can a person be expected to stay married to someone who doesn't want to be with them, and at worse, wants to be with someone else?"
I would not live with such a person. However, even if separated, I would still in reality be married to him. That is to say, the bond created by the vow would still be there; I would not be free to marry anyone else. I would have to hope and pray for his repentance, and the restoration of our marriage.
That's what "vow" means. That's what my mother and father meant, when they married each other. I just checked it out with my husband a half an hour ago: that's what he meant, too.
Whew! :o)
The vow of 'till death do us part' is broken by the other person when they tell you to get lost. There's no moral obligation to honor that after that point (reciprocal promises and obligations and all that).
I guess we disagree on the practical aspect of all this.
It's hard to imagine God wanting one of his children to needlessly remain alone and miserable while their rotten spouse behaves as if the marriage didn't exist anymore. What makes you think he would want that? What social value does that advance?
Makes no sense.