What kind of behavior of a husband can be regarded as having an affair with his wife's best friend?

I don't know. Tell a joke to open an awkward situation.

Wife: "Go to bed early! I'm too tired to talk to you today ... "Husband:" How can I listen? There are others moving in the room! " Wife: "You are on a business trip! I am lonely alone, so I asked my best friend (Xiaoxue) to accompany me. What! Don't believe me! Or I'll ask my girlfriend to tell you! " Husband: "No! Wife! I believe you, go to bed early! " After putting down the phone, my husband watched his wife's best friend (Xiaoxue) smoke all night. ...