Cuckolded By My Best Friend

A man suspects his wife of cheating on him.  There are multiple signs including that she is working late more often than usual.  She is wearing shorter skirts and sheerer blouses.  She is also wearing higher heels.  This last sign is critical since she has not shown a fondness for high-heels.  When he decides to do some detective work and goes through the laundry basket he finds lingerie that he has never seen her wear.  He is now convinced but he has no idea who she is cheating with.