Let me guess: He was tricked by the previous life's other woman into thinking that Cecil, now Liz, was either cheating on him, hating him, or some other bullshit lie and has no idea he is, or was, the cause of her death in said previous life. That's why he's so fucking oblivious, callous, or whatever other word(s) he represents.
Obviously since we're dealing with a Shoujo, we're dealing with misunderstandings galore. So it's gotta be something that's so asinine in its simplicity that once it's solved the whole drama up to that point meant nothing.