Well, maybe I'm wrong but when I refer to what the character of Mark Johnson is supposed to have done in the series (letting go of the past (*) after only 6 months, after Starfleet HQ declared Voyager and her crew lost, to date a woman who worked with him before marrying her). He seems to be the kind, "As the saying goes, out of sight, out of mind ans heart" and pretty soon!
In fact, that Janeway is found herself (with her crew) stuck or not in the DQ, would not have changed much with Mark Johnson. They would eventually separated, not because they would no longer love each other but rather because, as a pure product of Starfleet, her military carrier would always pass before her personal life, which includes Mark (**). And the latter, who is a civilian man contrary to Kathryn Janeway, would eventually get tired of her repeated absences (with missions which would endangered her) and so, the lack of a normal married life (with a wife & maybe children). Result: he would surely have ended up going elsewhere after a certain time and it would have ended in divorce!
(*) I can't imagine that Gretchen & Phoebe Janeway, Kathryn's mother & sister would have given up so quickly and easily to return to a normal life, if they have even tried to do it!)
(**) That either Mark, Chakotay (if he and Janeway have ended together at the end of Endgame & if he had been left free after returning to Earth, of course!) or someone else, who is in her life. By the way, please, notice that Kathryn Janeway, become vice- still bears her maiden name, in Star Trek: Nemesis, suggesting that no one shares his life with her.