I don't get what's wrong with this facebook account?

i have this friend on fb, we'll call him ben. well about a week ago, ben's facebook suddenly disappeared (i guess he deactivated it) and i even had my friends check for me, his profile didn't come up on their facebooks, so he had for sure deleted it and not blocked me or anything. well his facebook would reappear again and then disappear. but i noticed he hasn't been online because he hasn't been going on chat or adding people like he normally does. then i checked it just now and i'm coming up on his friends list, but it's appearing as though we're not friends because i would check my list and he's not there and when i search him up it lists the number of mutual friends we have because that's what happens when they're not your friend. but then when i click on his profile the add friend on isn't there and it still gives me the option to remove him as a friend. i can't tell if he tried to block/delete me and it failed, or he just isn't going on anymore or if facebook is just being weird.