Definition: Given a real-life anecdote of a complex ethical situation, generate a suitable title that describes the main event/root cause of the situation. Imagine that the given text is a social media post, and you have to write the title of the post, so the users can decide to read the main text or not.
Input: I had a fwb that I would have casual sex with regularly,  but I decided that I wanted a relationship and she couldn't give that to me.  I met with an ex-girlfriend and we decided that we wanted to get back together, so I stopped the fwb. I didn't tell her about the fwb but, at the same time, she never asked me about previous relationships/partners either.  Now, a couple days later, she asks me if I had seen any other girls and I told her I had casual sex before we got back together.   She flipped out on me, considers that I betrayed her and she's ran off crying.   I tried to comfort her, but she doesn't really want to talk to me .  

I just didn't think  it would have been appropriate to bring up, but since she asked I couldn't lie to her.  Am I the asshole for not telling her about my situation before we got back together?

not telling my girlfriend about a previous sex partner