According to Jim Recap: Take My Wife, Please
When Jim and Cheryl find opera tickets in the mail that belong to their neighbor, Bertram (Steven Gilborn), one of them is elated and the other is not. One guess who is and who is not. If you get it wrong, stop reading now.
Bertram, being a kindly older gentlman, offers the tickets to Cheryl when he sees how excited she is. But then she has a problem getting someone to go with her. Andy won't. Dana won't. You know Jim won't. So he suggest that Bertram take her. That's a great idea!
The only problem is that one day while the band is practicing in the garage, the guys start giving Jim a hard time about how even old guys still want to date and how that "little blue pill" can help them get things going again, and before you know it, Jim is jealous. So he waits up for Cheryl the next time the go out, because she is supposed to be in at ten. They come home at one in the morning. As Cheryl goes upstairs, Bertam lets out a little groan and Jim immediately recognizes it as an involuntary sound that men make when they want to be with a woman, so he chases him off the porch with a hose.
Cheryl, naturally, is offended, so she sneaks out the next night to go to the symphony and ends up at Bertram's house, where he fixes her wine, lights candles, turns on music, turns down the lights and... makes the noise. The worst part isn't that he hits on her, it's that Jim was right.
