Do you think this means he misses me?

Yeh it sounds like he misses you a lot. Showing up at your exhibition and giving you long hugs, wanting to see you soon and especially asking you to model for him to draw. it seems like he wants to be with you. He might just want to be friends, but i think he wants a relationship. If you both share feelings for each other, then there's absolutely no reason not to be together. Good Luck