What does it mean when a guys ask what are thinking after sex?

He likes you now

he wants to know if you like him too now

FWB never last - they either evolve into relationships or fade out.

Sounds like the possessive type; a few of my female friends have encountered this situation, and later we found out the guys wanted to see other girls, but at the same time, they wanted to make sure the girls they saw were only seeing him. So they gave the line of not wanting to be nothing more than friendship, and in their minds, that gave them the right to hook up with other girls; however, if the girl hooked up with another guy, then they got upset. Also, it could well be that he developed feelings for you, but maybe he is too 'cool' to admit them. Also, these type of guys think they should be the only ones 'doing' you, so could be just possessiveness along with jealousy. :)

Sounds like he is jealous. You seem to be more attractive to him now that he knows someone else is interested.
He can't have it both ways. Let him know that he needs to make his mind up, because you deserve better than that. ;-)