Some things in life are unspoken rules. I don’t know if people tell us not to do these things or if our common sense does. One of the rules is not to date your best friend’s ex unless you have spoken with them about it and gotten their blessing, or any close friend, for that matter. Others are don’t cut in line, don’t stand too close, don’t talk about your bodily functions, don’t talk about your life miseries and ailments on a first date, let people exit before you enter, don’t touch other people’s things, leave things as you found them, and on and on. We do these things because we are 8 billion people on one planet, and we have to all get along. Considering other people’s feelings and sensibilities before acting is a good and excellent thing and the best way for you to get along in this world, too.