This sounds like the beginning of an episode of Forensic Files.
Or some queer messing around with a strait couple
Jealousy
And the naive woman took the unsolicited ‘advice’ from a gay guy
Then I'm glad I never watched that show.
So apparently this guy did not agree with her views, and that was a “red flag” for some guy eavesdropping on their date. I’d have been more worried about the guy eavesdropping on the date.