im trying to help a friend......?

I would tell him the truth, because either way he's going to get hurt in the end. But if you wait and tell him later there will me more pain for the three of you. Your friend is actling like a player, and needs to tell him she has feelings for this other guy.

Would you want your boyfriend to like another girl, and his friend to know but not tell you? If he was thinking of cheating even? Because that's what it sounds like she's planning on doing. I'm not trying to sound mean, but I want you to understand, telling him the truth would be the right thing to do. You'll understand that at some point. if you don't now. Really, now I would just forget it ever happened, since he likes this other girl. Then it wouldn't be a problem at all. She shouldn't be so upset since she already has a caring boyfriend. If he isn't nice enough to her why is she with him?You'll understand that at some point.

Well lol as a friend you're obliged to cover up for your friend, the answer is obvious.

But I suppose you should dicuss the matter of the other guy and the boyfriend between you and your friend; If you feel like there's a moral dilemma or something about her having a boyfriend while having feelings for another !!

The truth always sets you free.