It's rude to pry.
John is at the mall food court where he's eating, and he can overhear the two nearby women complaining about their husbands.
John wants to say something about the women's conversation.
John tells the women that he can hear everything they're saying and that they should probably whisper if they're going to talk about personal things.
John tells the women that intimacy is very important in a relationship and asks them if their sex lives are up to standard.
The two women are grateful to John for pointing out that they're embarrassing themselves.
The two women are repulsed that a stranger would try to investigate how their sex life is going and get up to leave.