S. 2, Ep. 5 - Mary: I don’t have to marry him, you know.
Matthew: Yes, you do. If I thought for a moment that I was an argument against your marriage, I should jump into the nearest river.
S. 2, Ep. 9 - Matthew: You don’t have to marry him, you know. You don’t have to marry anyone. You’ll always have a home here as long as I’m alive.
Mary: Didn’t the war teach you never to make promises? And anyway, you’re wrong. I do have to marry him.