My S.O. and I are in an open relationship because he was a virgin when we met two years ago and is worried that he is missing out, but I can't help but be bat-shit crazy jealous when he hooks up with other guys or flirts with them. What do I do?

We have been together two years and I moved to a new city to be near him. I want to be as supportive as possible and have had my fair share of one night stands in my freshman year at college, but now I really just want him to love and appreciate me. He can differentiate sex and emotion but not sex and attention, and he cannot get enough attention. Am I over-possessive to want to call him mine and mine alone, or at least only share him if I am still involved?