<human>: would  some thoughts from everyone on this!

My girlfriend and I have been in an "official relationship" for a little less than a year now. Before that we were going out on a lot of dates for a couple of months and then we decided to take a trip to Europe together. I came back early but she did some more traveling. We left things open as to the state of our relationship when I left Europe and she continued on. 

So I just found out a couple of days ago that she had made out with some random dude at a bar in Europe. Should I be upset about this? And why did it take her so long to tell me? Maybe she didn't even have to tell me... On one side, there was no "label" as to the status of our relationship but on the other end we were constantly around each other and I would have considered us to be "dating" but not quite SO's at this point before the trip and sometime after the trip when we were talking, she assumed that we were "exclusive" as of after the trip. 

Sorry for the labels and if this seems a bit stupid but I'm curious on other people's thoughts. I don't consider this cheating but I'm still a bit hurt...

Give me a shortened version of the text
<bot>: Found out my now gf made out with some random dude at a bar when we were seeing each other/kind of dating (whatever you'd call it).