Bob loses Alice and, despite trying to just move on with his life, becomes sufficiently twisted and embittered that if someone put him in a position to get revenge on her attackers, there's no telling what he'd do.
Bob has been bullied so much that he becomes a bully himself.
Bob has suffered so much abuse, he snaps and is clinically insane.
Defied: After Alice's death, Bob gets therapy so he won't engage in any of this type of behavior.
Deconstructed: Alice was a Person of Mass Destruction killed with the support of essentially the entire world, with only Bob who looks up to her. As a result, nobody sympathizes with Bob's rebellion, and it ultimately comes across as pointless and stupid.