Well, Kolyma is really quite a distance from Daventry, and that's where Mother was imprisoned--or near enough to Kolyma, really, thanks to a magic doorway. So everyone knew that when Daddy set off on his adventure, it was because he was seeking a bride, but rather than going all the way back home after he rescued her, they just married right away in a monastery in Kolyma. So by the time he finally came back to Daventry, he and Mother were already long since married.