I think Alicia's issue is she still sees Denning as the "monster" he was.
I mean, he only recently changed, at the very most, a few months ago.
So his new persona is something that befuddles her. But she still keeps the idea that he'll revert back to his old ways in the back of her mind; like a lover scorned.
I'm sure we'd have a generic otome manga plot had Denning reincarnated earlier in his life.