No, you're your own girl. He is just lucky enough that you choose to share your time and life with him.
That's his prerogative. If having multiple boyfriends is something you want in your life, and being one of multiple boyfriends is not something he wants in his life, then no one is forcing him to be your boyfriend.
Sounds like a dependency issue. He should be his own life.
How is it possible to share or not share something you do not own? If he accepts that he does not own you, then the natural consequence is that he is not in a position to dictate your life.
Finally! What he wants for his life. That's a good place to start.
So you and he need to sit down and acknowledge that you want different things, and then figure out if it's possible for you to both have the things you want while remaining in a happy, healthy relationship together. Clearly someone is going to have to give in a little if that's going to work, so the question becomes how much are you each willing to compromise?
I bet they do. I would feel the same way in your situation!
That's a coercive technique. I personally would question any situation where someone was so quick to throw me away completely just because I want to change the parameters of the relationship.