Your boyfriend sounds immature and quite possessive. If I were you, I'd break up with him for thinking he could dictate to me how I conduct my relationships. Even though he says it's not about ownership, his views that you are something he "shares" just a little with people, and that you are not allowed to live your life as you see fit, screams ownership very loudly. People can't make rules for other people; they can only establish personal boundaries for themselves. DTMFA.
The world opens up... when you do.
Oh, oh, can't you see? Love is the drug for me. ~Bryan Ferry
"Love is that condition in which another person's happiness is essential to your own." ~Robert Heinlein