Lyric discussion by Cyberghost 

Cover art for It's Not Your Fault lyrics by Athlete

I think it's about a car accident, where she was driving and possibly caused the accident, and he's still alive but she has died and he's in shock trying to understand what happened, part of him realising that she's dead and trying detach himself from the feelings of loosing her.

You're on the right track, but it's more of a figurative sense. He's stating that their relationship had hit a point of no return. Like a car crash, she's dead emotionally and romantically with him, but he's still "alive". She's moved on (especially with the dancing up to her bedroom part meaning she's been sleeping with other men), but he hasn't. He's tried to reconcile, but now he's realized that he just needs to let her go because he can't "save her".