I appreciate how he noticed he fucked up big time
"trust is built in drops and lost in buckets", there is no way he can fix this in one day, the moment she lost all interest in him was a point of no turning back, at this point even if he explained it all her reaction would be a "oh, sorry for the misunderstanding" but it wouldn't change anything, he needs to rebuild the whole relationship from the bottom.
this is even worse than if she was mad at him, or if they where strangers, when they say "the opposite of love isn't hate is apathy" this is what they mean, he is working from the negatives at this point, she built a wall around her emotions where she doesn't care what he does, he can't make her sad but he can't make her happy either because of this, if she was mad he could work on it little by little but since she has totally cut him off, he needs something big just for one more chance, small things won't work and just be brushed off.