Um. That's a good question. That seems to be a tad old-fashioned. I suppose it's kind of chivalrous? That the man would accept an uncomfortable place to sleep for the night while the fight blows over. You could also make an argument that it's sexist. That a woman is so unable to control her emotions that the man has to leave the bedroom because she'll... explode or smother him in his sleep.
Also, I believe that it's never a good idea to go to sleep angry. It just prolongs a breakdown in communication. Most fights can be resolved by one party just listening and acknowledging whatever grievance is being expressed. If not resolved, then the severity of the fight can be reduced. The only thing that admitting that your boyfriend or girlfriend has a point is pride and pride is self-esteem with a facelift. No one is ever 100% right. Except possibly moi.
I feel that this "tradition" is a messed up way for a woman to exert power over a man. It is SO degrading to be sent to sleep outside the bedroom, like a dog! It's my opinion that if a couple is actually in love and values their relationship, they will share a bed despite being in a dispute.
i think it goes back to the idea that, no matter who the bed physically belongs to, a woman let's a man into her bed. yes, it's old fashioned, and probably a bit sexist, but it comes from the idea that it is a privilege to be allowed into a womans bed. and when she's mad, it is revoked
whenever my parents got into an argument, being stubborn that they are, they both would refuse to be the one to sleep in another room. my father never really learned to apologize and my mother would just keep repeating all the hurtful things she heard from my dad and hurting herself more. the tension in that wing of the house used to drive us insane. They kept telling us how much they despised each other. i was pretty sure their marriage would end(horrible to think of your parents that way, but it was that bad at multiple times) but they are still 25+ yrs and going strong. somehow maybe their stubbornness helped....
when my ex and i would argue i was actually the one who slept on the couch, i didnt want to be anywhere near him, so that was my way of telling him