The guy I’ve been seeing for 4 months slept with someone else. do I have a right to get upset?

I feel like I can’t be mad because we’ve never had a chat about being exclusive it just hurts. I haven’t slept with anyone else even though I’ve been living abroad the past month because I knew how much I liked him. I kind of feel insecure knowing he has because it makes me feel like he has doubts about me. Or am I being dramatic? Did he just sleep with someone because he needed a sex fix and not because I’m not good enough? Also to add to it he never told me until tonight but it happened weeks ago. I’m not sure if my reaction is valid or if I need to be more understanding to him
The guy I’ve been seeing for 4 months slept with someone else. do I have a right to get upset?
Post Opinion