When your wife emerges from his apartment the following morning, you will have become a cuckold, and she might be pregnant.
Your wife is making it clear to you that if you truly love her -- which you both know you do -- you will step aside to give her and your best friend the time and privacy they need to explore their feelings for each other.
What sorcery is this !
I have no freaking idea but whatever it is works like a charm 👍