I was in High school once.
I had friends that were on and off again that we had no idea if they were on and off. Yet, when they did date other people it was never the other person's friend. I felt bad for the person they were dating. Why? It felt like they were just being used until the other two got back again. I thought that itself was wrong. We probably seemed semi cold to the ones they were dating because we as a group wanted nothing to do with it. We also found ourselves distancing with them.
I had friends that would rebound after a break up and regret that
I had friends that were cheated on. Somehow I never liked the person they were dating. I did my best to support this friend. I can tell you that they never spoke to that person again.
So imagine Jughead why should he forgive Archie his best guy friend who is with Veronica? Why should he forgive Betty who he has loved non stop and tried to do everything to fix it if they had a fight.
Why should he? Cause they had a moment? Cause nobody believed his fake death they had to have Archie and Betty? Yet they all were in it at this point. He probably didn't like that idea. Still insecure and that's why he asked Betty again.
So for this musical that should be Kevin's time to shine. You are having his two best friends betray him. Almost like season 1 when Archie broke into his house and Betty lied about her mother's motives. Why this episode? Why do it anyway!?
There are other ways to create drama if it's true cheating does happen but most people that do go back with the person that cheated never trust them fully.
So if Jug's character is just alright cool. With nothing to it that's not okay. For Betty to do that in the first place is like wtf.
I feel bad for Veronica just not as much because they all weren't childhood friends.