Because of Winn-Dixie
How we cite our quotes:
"See," I said, "you don't have any family and neither do I. I've got the preacher, of course. But I don't have a mama. I mean I have one, but I don't know where she is. She left when I was three years old. I can't hardly remember her. And I bet you don't remember your mama much either. So we're almost like orphans." (3.2)
Opal feels connected to Winn-Dixie because they've got parent problems in common. Later on, Opal feels the same connection with Amanda, who lost a family member. So although abandonment pulls people apart, in some ways it also pulls people together. Kind of like those finger trap games.
"I think the preacher thinks about my mama all the time, too. He's still in love with her […] he's still hoping she'll come back. But he doesn't tell me that. He won't talk to me about her at all." (3.8)
The preacher seems to believe ignoring his wife's presence/absence in his life will make her influence just go away. Reality check, preacher-man. You're not going stop hurting, and Opal isn't going to stop wondering until you man up and face what happened.
"She loved you very much."
"But she left me," I told him.
"She left us," said the preacher softly. […] "She packed her bags and left us, and she didn't leave one thing behind." (4.18-20)
Here's where we start to see the depth of the preacher's sorrow. It's not just that his wife left, but she took everything. We're not just talking the remote and the pillowcases. She took a piece of the preacher's soul with her. Just don't ask him to admit that.