In Fascination, he resigned and offered to follow her back to Bajor, then to wherever she wanted to go next, particularly Earth. She told him that she appreciated what he was doing, then told him to go get his letter back before Sisko saw it.
Having been the wife who follows the husband so that he can pursue his career, I feel for Keiko. It's very hard giving up the life you have built to move somewhere you didn't choose and maybe don't even want to go to. It's hard to start over, build a home, make friends, raise children without support. Your husband is happy, and that's good, but you're alone except for him, and he's busy with his job (as he should be). It's just tough. I think their marriage is solid and good and as realistic as possible for being set in the 24th century.