I'm thinking of potentially ruining my mother's only long term relationship by interrupting her during sex
Why would you interrupt them during sex?
I think that is the best time to do it.
You shouldn't barge in while your mother is having sex. Seeing your mother have sex would scar you mentally. Is it worth it?
I'm curious on what's with the uncomfortable silence.
It is really rude to interrupt people in the middle of sex. People might label you as a pervert or something worse if you do this.