asses yourself if the kiss you have done is a moment of passion or do you have feeling for the guy/girl you kissed? if it's the first its still cheating however it is the lesser evil because you were horny... if its the second then you are a big time cheater... being in a relationship involves love... as long as that love is still whole its still ok but if you have feelings for another and you kissed then its time to really think about it!