I've noticed I get sort of upset, and grumpy when my boyfriend invites one of his friends to our game, am i too possessive?

Salty is a better term for how i feel but, for example on minecraft, we usually have one server so me and him can be cheesy and make our own things without his friends joking with him about it, we also have a world that we play with them.
But before we can actually get anywhere in just our world, he invites them over and my mood sort of plumits.