What could be instead of side walls?

i've got a living room where the walls are not facing each other equally. there is no place where it's possible to find equally placed side walls. the system is standing right now in the middle and speakers only moved off the rear wall but placed in very large distance from the side walls.
should i use some immitation of side walls arround the system or it's even better not to have any side walls arround?
currently i experience that the stage is out of focus and floating chaotically during reproduction.