I disagree slightly with cdwjava on this. The general rule is that each co-owner of property has the right to possession and use of the property. Thus, absent some court order preventing him from access to the property or some circumstance in which he has given up his right to possession (e.g. renting out his interest in the property, thus giving the tenant the right to possession) he presumably may move back in once the restraining order expires. If she doesn’t want to risk that, she needs to see her lawyer about putting a permanent restraining order in place.