We are thinking from 21st century view of arjun
Arjun had many wives not only draupadi
So he may be like its ok if they insult draupadi i have many other wives may be
Or hes like i am not her only husband so let others take care
Like children, everyone thinks let other take care of parents finally hardly anyone does ---- just an example
Arjun may not be in love with draupadi like hes with subhadra may be
Or Subhadra is his cousin and best friend sister so he will be more protective of her than draupadi
Look he loved abhimanyu too more noooo............you love the mother so love son from her too
Imagine if subhadra was there instead of draupadi, to hell with all rules of those times krishna and arjun would have finished everyone than and there is it not?
Second is yudhistra orders, those days elder brothers order is like Gods orders they do not disobey
Anyways i feel if it was subhadra arjun and kkrishna would not have bothered about yudhistra orders
So it all boils to how much you love the person truly?
Imagine instead of draupadi kunti is there, how would pandavas react?
If you truly love a person all rules are broken for them if not you say these are rules sorry and sit quietly thats all
I think bheema loved and respected draupadi more he was truly angry and spoke for her despite brothers orders
Bheema is that innocent soul who will not calculate situation and speak like yudhistra and co