Mysteries of married life

In cleaning off the pile of paper on top of the microwave, I found a piece of hotel notepaper with "Andrea, room 453," and a phone number written on it in unfamiliar feminine handwriting.

When the spouse came home from the gym, I showed it to him and said, "I know all about your fling with Andrea."

He said, "Hey, how do I know you didn't have a fling with Andrea? You could be accusing me to deflect attention from yourself."

So there you have it. One of us had an affair, but we can't remember which one.