Just entering into the house would have broken a court order. Taking anything, even if it was his, would be burglary
I wonder if that depends on the state. Years ago my youngest son had been in a relationship with a woman. When they broke it off, he wanted to be able to pick up his stuff. She had put it in the garage. She was telling him he couldn't get any of it. He called the police, and they escorted him to the house, and advised her that she had no choice but to let him get his property. They had bought the house together, and she had taken up with her old boyfriend, throwing my son out of the house.