I am new to being a DM. A few months back, three of my friends wanted to play D&D for the first time so I offered to be the DM. Everything was going fine until our most recent night.
Basically we were coming to end of the quest when they would fight the big bosses. We almost had a total party kill but luckily stayed alive. As the villains fled, the fighter threw an explosive barrel at them to see if he could stop them getting away. He was unsure if this was going to work but by luck it not only hit but did critical damage. One of the two villains was dead and the other was close. The fighter wanted to plunge his sword into the villain and end this. But the Rogue said he wanted to kill this villain. They argued and got nowhere. I settled them down, and decided to randomly determine who should kill the bad guy. The Fighter wants to kill the bad guy because he just saved his friends and he wants to end the villain. The Rogue on the other hand wanted to kill the bad guy because he felt he had earned it.
I said you will make a d20 roll to see which of you kills. They unhappily agreed and they rolled. The rogue lost so the fighter got the kill. The Rogue's player declared that he is done with this and has his character pack up his things and go. He left the party. I was unsure if he was serious because I have never heard of this happening. He said he was done with D&D.
So we ended the campaign after a quick wrap up and an awkward silence set in. I pulled the player aside and tried to figure this out. He told me that he deserved the kill because his character did the most, and the fighter stole the kill from him. He said that with time he would simmer down and he would join up again with the campaign later. But should I let him come back?
I tried to tell him not to take it seriously and that how he acted was wrong but he tuned me out. I know that the fighter feels terrible because he, and everyone playing, didn't realize how important the last kill was to him. So before I left I told him that I understand that he is angry but he should call the fighter. I explained that maybe if he expresses his feelings then the two of them could comprise or come to an understanding.
I plan to call both the fighter and other player to see how they are feeling and their concerns on the matter. I have time before our normal scheduled session because we are getting some new first time players joining us and I need to make the characters and such.
I am unsure if I should let him back when he has cooled off and make a rule that he can't do this again? Or tell him that he that really was rude and I not going to play with someone like that?
Does anyone have any advice on that matter?