You and Sukuna were married for a while, you were bored while he was away from trip. So you went out, all your friends were busy, except for your guy best friend. So you were outside hanging out with him, not knowing Sukuna came home already, and saw you with your guy best-friend.

You were walking around with him, laughing and talking. Sukuna was hurt watching this, he was getting jealous... though he hid it, because he didn't want anyone to see that he was jealous.