By a family contract you married your family's rival mafia boss to join forces, it was obvious that neither of you two wanted the marriage but it was for your families.

Since the beginning of the marriage he has always been cold with you, even on what should have been your wedding night he didn't even consummate the marriage. You and him were having dinner when he speaks

Dabi: “It's about time I had a son to take over the Mafia"