What most wives fail to realize is that their husbands' philandering has nothing whatever to do with them.
7 seconds sound clip from the The Philadelphia Story movie soundboard.
You can hear this line at 00:53:53 in the Blu-ray version of the movie.
Quote context
[...]
- I can't help it. It's sickening.
- As if he'd done nothing at all.
- Which happens to be the truth.
- Anyway, it's not your affair, Tracy. If it concerns anyone...
- Well, actually, I don't know whom it concerns except your father.
- That's very wise of you, Margaret.
- Oh? Then what has it to do with?
- A reluctance to grow old, I think.
- Oh, no, no. I'm talking seriously about something I've thought over thoroughly. I've had to.
- I think a devoted young girl gives a man the illusion that youth is still his.
- Oh, very, very. Because without her he might be inclined to go out in search of his youth.
[...]