Is this considered cheating?

My girlfriend and I live 2 hours apart. She is taking a night class. She calls @ break time 7:00pm to talk and she calls during her drive home about 8:45pm. The break calls ended. When I asked why she stated she was having discussions w classmates and I was fine w it. The 8:45 calls started becoming 9pm calls then 9:15pm calls. She explained that classes were extended. I was suspicious. The next week a friend of mine parked in the parking lot and waited. She got out at 8:35pm & got into her van w another man. They stayed in the empty parking lot together until 9:45pm. She called me after he drove out and told me that class got out late! Later (after I told her I knew the truth) she came clean & said that he was just a friend (married) and he was having some problems & he needed a friend to talk to.............