When you begin to go to milongas, they may feel foreign and you may not know what to do. You may not even know what kind of a place a milonga is.
A milonga is just like a nightclub, and the same codes of conduct as in going out at night are applied. There are specific codes of behavior such as cabeceo, line of dance, and etc., but basic social behavior rules are the same.

If somebody tells you that you have to dance with him/her because everyone is supposed to dance with everyone at a milonga, that is a lie. If somebody touches your body and you felt bad but if that person tells you that you have to bear with it, it also is a lie.