Is kissing in a dare cheating?

My girlfriend of 1yr and 9months went to camp over the weekend and while hanging with a bunch of her friends they played truth or dare. Also, she's 20 yrs old. I'm 23 and was not at camp. Everyone knew she was in a relationship as well as the other guy was as well. She was dared to kiss on the lips and french kiss the other guy 3 times. First was a french the other 2 just on the lips. She of course did the dares. She says the kisses meant nothing, that it was just a game and was not cheating. That because it was a dare it was not cheating. She also says I should trust her enough to know it meant nothing and wasn't cheating. I however feel that it was betrayal. All her friends and others she asked say it's not cheating. Everyone i ask say it is. I feel that saying a dare makes it ok to kiss would be the same as saying having because of a dare would be the same. She says kissing is ok but would count as cheating. What do you think?