I always thought this was a little wrong of Bill
Near the end, after Grey picks up Sue from the CPS agency and brings her home, the two of them walk through the door and find an envelope addressed to Sue, containing a note from Bill and Sue's ring. Grey reads the letter to Sue, which simply says, "I'm in the living room".
WHY did Bill do that? I know it set up that sweet scene thereafter between the three of them where they embrace like a family, but Bill had to know when Sue saw that letter, she'd be thinking he ran out on her. It just seemed kind of a mean trick to pull.