Why can't he compromise

So this Sunday is my cousins baby shower. And I will be dropping my bf off at work and then going to the shower. He expects me to only go for an hour and leave to meet him on lunch so he can sit in the car...

So I'm supposed to miss 2 hours of the shower so he can sit in the car on break...

Why can't he sit in the break room??

Not go mention the only time I leave the house is to go with him somewhere, go to the store, or go pay bills.

But god forbid this one time I want to do something I have to limit my time there for him... Why can't he compromise? Why do I always have to make the sacrifice....