Does this include the plot points where there’s a misunderstanding in a relationship? Like where a girl sees her boyfriend hug another girl but doesn’t know it’s his cousin or something and instead of talking about it just ignores him and so he ignores her and it’s just dumb and entirely avoidable?
That’s gotta be its own trope

It is, they even reference it in the IT crowd.

“So I followed him to the restaurant.”
“She was his sister, wasn’t she.”
“Yeah.”