How is that? If she wants to leave him what is he supposed to do?
This is true. This marriage was the third for Marta as well. She's probably got some hefty baggage of her own as well.
If she wants to leave him, and he doesn't want to break up his marriage, the word you are looking for is "no."
"No, I don't want a divorce. I can't keep you from leaving, but I won't make it easy on you. I don't believe in divorce. We promised to stay together through thick and thin, and this is just one of the thin times. It will get better. Whatever your problem is, we can work it out. Stick around, the best is yet to come."
"How is that? If she wants to leave him what is he supposed to do?"
Was it her that decided to leave?...I would like to know because that would make all the difference in the world!