Having both parties staying in the home is an obvious source of friction and trouble. The one indisputable reason to remain in the home is if there are children. Voluntarily moving out and leaving the children in the care of the other parent gives them a strong argument for primary custody. The judge will reason that if you were a concerned parent, you wouldn't have left the children with the other parent unless you felt they could take adequate care of them. Moving out without good reason is often the single largest blow to a custody case.
Staying in the home can be the source of major problems, such as physical confrontations, ongoing fights and arguments, etc. Staying also provides numerous opportunities for false allegations to be made.