Most Helpful Guy
Sometimes, you just don't feel like being associated with a person anymore. Don't see an issue.
Most Helpful Girl
Personally i think it could mean a lot of think it just depends on how you look at it. It could means he's finally over her/him completely that he doesn't see her/his significance in his life. It could mean he has a new boy/girlfriend and he/she doesn't want HIM to have his ex on fb. It could mean he hasn't been able to move on from his ex and the only was he see fits is to erase his ex from his life to get a clean slate and move on. Its really how you look at it so you never know for sure until you ask him about it coz all this is based on assumption. Hopefully i helped... good luck.