if pilots you share your cockpit with are behaving unreasonable, and impulsive and started to argue and nerves are getting tense?
First question you need to ask: Are you the one causing the behaviour...I've certainly had one or two overly proactive "heavies" and even P2s who by their actions, though possibly well meaning, have interferred with proceedings/confused the operation and who have needed telling to calmly but politely to stick to SOPs ......they probably could think I was being irritable and impulsive but....
Secondly: if you walk onto the Flight Deck and into the middle of an apparent disagreement try to get the full story before you start offering councelling ot threaten to get off.........
But finally, if you think it is a genuine problem that is interfering with the safety of the flight then yes, you have to put a stop to it.