Then why bother with telling anyone anything? If she chooses to marry him, and he chooses to ignore the fact that she is a multi-timing Eta Omicron(think of the letters) then that is their respective problem. The best case scenario is her telling him, NOT you. If you are not really friends with either of them, getting involved is only going to be a pain in the butt and cause unnecessary drama on your side of the yard. It's not up to you to be the morality police. If what she does really bothers you, don't hang out with her anymore, you said you're not really friends...and that friends are expendable, which is kind of sad in an of itself...why would you want to be friends with people who you view as expendable?

that's the thing
i've tried to stop hanging around her
i have changed my cell phone number 3 times
(not because of her but because of a case of the ex)
and she calls other people to get it

several times i have ditched her at the bar

and contrary to popular belief, i haven't decided what i'm doing
other people have been pressured to tell as well
i'm just wondering if everyone would be singing the same tune
if they were in mark's shoes

This is such a tough one, girl. If she were sleeping around, I'd say that you'd have to say something, for health reasons if nothing else. But since it's just making out, is it really physically endangering anyone? I guess I would talk to your friend again. Tell her that her behavior really bugs you and that you feel bad for her man. Encourage her to work through these lack-of-romance issues with her man instead of sucking face with random people.

Maybe you should break up with her. Be direct and end your friendship instead of trying to ditch her at the bar. It is hard, but sometimes it is necessary.