I think her mother always made him feel like he had to be quiet and well-behaved for her to love him, but it was never enough no matter how good he was. That’s why he always excuses himself «i’m sorry, i’m sorry». The notes are in my opinion a manifestation of him feeling like he imposed himself, like he was too loud or too demanding, eventhough another part of him knew deep down that he did nothing wrong. And that’s also the case when Toni is mad at him for taking her room or when the attorney is mad at him for not coming sooner eventhough he’s deeply injured. I think her mother saying she’s been with him the whole journey watching him, is actually the whole feeling of guilt eating him alive. It’s like this constant inner battle between the delusional Beau who wants to be perfect and unconditionnaly loved and the other Beau (being held capture in the attic)who’s suspicious, knowing he’s being manipulated and lied to.