Unfortunately can’t remember if this was in a movie or TV show. But there’s a particular scene where a younger guy goes to a party with older people (one might be his brother?)
The younger guy sees an older girl he’s attracted to, but thinks she is with one of the older guys who brought him to the party.
Later the girl takes the younger guy aside and comes on to him as she caught him looking at her.
Can’t remember anything else about it, just this scene.