I'm with Ariakis; the "friend" was being a jerk, and owes Tomte an apology, given that the rules of that friendship are clearly that they aren't to be smooching each other's partners. What I, or other poly- people, might think of those rules are sort of beside the point, since they exist in this case.
Originally Posted by Tomte
How to react? just being honest is right I think and say I donīt care, but do I not have to do anything. I wanna give this situation a more important role, hard to describe. what do you think?
Yes, you can say "I don't really feel angry or jealous, but I still think what happened was somewhat important." The root of the problem is that you are not in the kind of relationship you want to be in, whereas she is and nevertheless still gets to smooch people. But, look, this relationship is going to go through a big change in two months. I wouldn't put a lot of time and energy into processing a kiss. Try to enjoy what you've got while you're spending these last couple of months, and then think about what you might have learned from this experience.
I'd also suggest that next time, you don't give up on getting the kind of relationship you want just because you're getting "all you need" two months into the relationship.