<human>: Can you succinctly summarize the text in 1-3 sentences?

Hi everyone!

So my boyfriend goes out to bars every once in a while with his friends. Last night, he informed me that one of his friends (who is in a relationship) got the number of their waitress and invited her to hang out sometime. I replied with something along the lines of "Wow, so he's cheating on his SO?" and it started this huge argument about when and where it's ok to make female friends.

I personally feel very weird about my boyfriend essentially picking up girls at bars to make "friends." He thinks I'm being insecure, that you can make friends anywhere, and that I should have no say over when and where he can make friends.

My boyfriend did cheat on me many years ago, but I don't feel that that instance is fueling what he calls my insecurity (he does). To me it just seems like common sense that this is something you don't do. We are also long distance (~3000 miles apart) and are planning to move in  together this summer.

I really would like to understand what I'm missing here. IS it possible to get a girls number (specifically at a bar) and have a friendship develop from that? Is it unreasonable for me to not be ok with this?

This is my first relationship ever and I'm just lost. I'm surprised something I think to be blatantly not ok is something my SO thinks is totally acceptable.
<bot>: My boyfriend thinks it's acceptable to get a girl's number while bar hopping, I do not. Am I being unreasonable?