Thing is, realizing you might be going down a bad path can be extremely difficult. Even if, as you say, the person you care about the MOST in the entire world says he is done with you, that doesn't necessarily mean you are going to suddenly flip the page. Depending on how bad things are, how you...
I can actually see something like this being how the story was meant to play out. Aside from the memories being blocked due to guilt. Seeing the accident the guy was in, full amnesia would not be surprising, regardless of any emotional trauma.