If you're really mad at the person you sleep with, like so mad that you think you can't even bear to sleep with that person or maybe just so mad that you want to Send Them A Message by not sleeping with them, it's probably a good idea to alert that person to the level of your anger sometime before you go to sleep on the couch.
Otherwise the next day you find yourself with a crick in your neck, explaining to the person who totally missed the whole thing that they slept alone because you were an angry angry little red hen, finding your grain of anger and growing it up and baking a loaf of resentment and ruffled feathers while the other person slept peacefully away, and at some point in your angry narrative you will realize which one of you was ridiculous.
Then one of you will have a good cry and both of you will have a good laugh and you will be very glad that the couch is as comfortable as it is because otherwise you would be up more than a crick without a paddle of reason, and that night you will sleep together like sensible people; I mean all things considered it's not a bad way to spend a fight, but wouldn't it have been better if... no, actually, this is a happy story all around. Another anecdote, an annecdote, the antidote to the sadness you would carry around if you didn't have the sense to shake it out, hold it away from you, realize that it's a color that has never suited you anyway, no matter how flattering the cut.