If the spouse (either the husband or the wife) is sincerely wanting and offering to continue the existing marriage, he/she is not preventing anyone from being married. And “unhappiness” isn’t a basis for divorce. (Hashem knows how many people regret having gotten divorced and are more unhappy as a result.) Rabbeinu Gershom specifically gave wives the right to decline to divorce if the unhappy husband wants to divorce her. (The husband had the equivalent ability beforehand.) Clearly R”G (and the Torah) say one spouse can insist on making the existing marriage work against the desire of the other and the motive for doing so is not “revenge” and can work.
Ben Levi has my vote.