I saw my mother flirting with other men on numerous occasions since I was sixteen but have never mentioned this to my father.
It’s pretty harmless and its not like she ends up going home with random strangers. Yet again there a lot of sexual tinged conversations and tons of indecent proposals and suggestions. If my wife would go the pub, get as drunk as her and do the things my mother does with these men I would probably accuse her of cheating or of not caring about me nor her family.
The reason I never told my father is that he won’t believe me anyway or even worse, not care. When it comes to subtle flirting, it’s very hard to get proof. Besides he is head over heels with my mother and thinks she is the greatest person ever. Me marring that idealized image will unleash so much anger directed to me, that I don’t think it’s worth to take the risk.