
Most people think "being nice" means just "having a civilized conversation", and that's perfectly acceptable. If your boy/girlfriend is uncomfortable with just that, they should give you the benefit of the doubt and say sth like "I will trust you to tell me if there really is anything I should be worrying about (about you and your ex)" which is a show of good faith. This is because sometimes you just can't exactly help running into your ex pretty often, if both of you study, work or hang out in the same places... And if that's the case, then your boy/girlfriend should understand that if that happens, you are socially expected to be civil and say hello... as ignoring them or treating them codly in public will only make you look like a bitch in front of other people (unless those other people are bitches themselves) so I wouldn't recommend sacrificing your reputation just to avoid angering your boy/girlfriend... They should grow up and realize that this kind of minimal civilized with ex lovers can't realistically be avoided in this day and age.
Ughhh when you have a boyfriend or girlfriend, you cant be so nice other people. And if there is guy who you made sex with him or he love you. You cant be nice your ex ughhhhh