I'm a man. It's not the fact that he is acting as a wingman. It's who is acting as a wingman for (infidelity).

If it were some friend who was super lonely who really needed help meeting someone, it would be an act of kindness.

But his buddy sounds like he doesn't need a wingman at all, and he could get in him in situations where he makes a life-changing mistake after too many drinks. Like if she had a friend that needed to be entertained.

If his friend wrecked his own relationship, how careful do you think he will be with someone else's?