Bonnie had a hard time letting go.
Between her back injury and the relapse that followed, Bonnie went through a lot this season. It's no wonder she didn't take kindly to the idea of Christy moving out. The Plunkett matriarch even blocked the doorway to convince her daughter to stay put.
However, Christy explained, "The road to happiness leads away from your mother," which meant Bonnie just had to loosen her grip and let her daughter grow.