He took a girls number..

So I've been dating my boyfriend for 3 months now, we were friends for 6 months, then roommates for a year before we started dating and really know each other and I trust him completely. I also know he's crazy about me. But last weekend he went out with our group of mutual friends and to encourage a shy friend to talk to a guy he approached some girl, and ended up taking her number. Now, our friends still don't know we are dating (we prefer to keep it this way until we are sure this is going strong) and I found out about it through a girl friend from the group asking him if he texted the girl the next day. He said no and laughed. When our friend left, I guess my reaction was a bit harsh but I was entirely sarcastic about it and angry but more in a silence treatment way (just my introvert personality). He explained to me what happened and also that they mentioned it in front of me before, which I seriously don't remember at all. But then again maybe I wasn't paying attention when the joke was being made, I really don't know. I believe he's not cheating and not texting her but I just feel disrespected in a way. I have feelings for him now, and really not sure how to handle the situation. Things have gotten colder between us since that night and I'm wondering if it's my fault and should have just acted as if it was funny. I keep thinking he could have done any other thing but that to help our friend out. Help please. 🤕😰