I know I've asked before, but would like more opinions?

He could possibly want you back. Alot of guys, sadly, try to hide their feelings & seem as if they don't like you, so you can want him. I guess it's kind of like manipulating witg your feelings. He also seems like he could be jealous of your friend. And depending on the guy, he could also be asking you about sexual things to see how over him you really could be. Other guys just like to be nosey for the fun of it. I suggest you have a talk with him to see why he's been acting the way he has.