[souffle]

Sometimes they will stay together. Some lines are more placid and laid back and also males often stay longer than females as a pair.
However there can be issues as if they do 'fall out' it can be very sudden and very, very vicious in that they can fight to the death. Often pet owners don't see the signs that something is not right and it can be prompted by something very simple like a different scent when handling. You need to be on alert all the time - friends I know with pairs will even sleep with them in the same room in case they start battling and have a water spray bottle by the cage to startle them in to parting and a jar to scoop them straight out. I wold be uneasy living with that level of uncertainty myself. Even when mating a pair I was up all night fretting over them in case they fought.
A single sex pair is not a natural situation and this wouldn't happen in the wild for example. You do need to be on alert at all times or make the choice of risking it or separating now and removing the chance of a fight.