I'm not going to give into my older roommate's demands about my gf
Do they make you feel uncomfortable with their demands?
No, the way he treats the gf is unbecoming and wrong.
If this is how he treats your girlfriend then you should stick up for yourself and shouldn't let him control you. You're doing the right thing.
Thanks for understanding.
No problem. Probably you should find some other place if your roommate is becoming too demanding.