Most Helpful Guy
The best advice I can give you is this: ask your boyfriend about it. If he's okay with it, then it is NOT cheating if you kiss a girl. However, if you do it without his knowledge and consent, then that IS cheating.
Explain to him also WHY you want to kiss a girl. Ask him what he thinks of your opinion about this situation and see if you can find a halfway mark if you REALLY want to kiss a girl.
Hope this helps. Go for it!
Most Helpful Girl
I think it depends on how your boyfriend feels about it. Surprisingly, some would be really upset, others would just be upset if they didn't get to see it.
My boyfriend encouraged me to hook up with a close friend who kept hitting on me, first time I ever had birthday sex. Depends on the guy.