Is this a betrayal why or why not?

He didnt tell me about his married female lab partner wanted to stay in touch when cl ended.She wanted to see what nursing school was like she wouldnt be going till the following year if she got accepted.She wanted to call he said girlfriend wouldnt like thens he said what abou email.So he did but never told me.I found out after he stoped emailing her.He said it was every few montsh about school.And he did meet her in grocery store parking lot to sell a book maybe there for ten min to tell her about the cl .Betrayal or not?Why or why not?