Right. In a mostly-empty theater, I’m going to get a little freaked out if any stranger chooses to sit in the seat next to me.
If it’s an attractive female, I probably wouldn’t object. Except that my wife is likely seated on my other side, and she most certainly would!
These are not examples of sex/gender stereotyping. They are examples of “social space conventions,” which vary by culture. Different cultures just feel comfortable at varying distances.
It is said that at a diplomatic party, it’s fun to watch an Englishman or American conversing with an Arab.
The Arab’s comfortable distance for casual conversation is at least a foot closer than the American’s. So he take a half-step forward because he subconciously is too far away. This makes the American feel vaguely uncomfortable, so backs up half a step. In half an hour or so they’ll work their way clear across a room.
These cultural conventions are neither right or wrong, they’re just different.