Have you tried to invite your Chinese roommate to a party? Was s/he very hesitant? Did s/he eventually turn it down?
Chinese students studying in the U.S. are very new to this kind of social life. Some of them may be quieter, but some of them, as outgoing as you are, may just have different preferences when it comes to "having fun."
We encourage Chinese students to try to party with their American friends. It's hard at the beginning because you may not get the jokes at the party or you feel awkward and too self-conscious. It will get better! Don't give up if you really want to experience American college life.
For American audience, we encourage you to be a little more aware of how your Chinese/foreign friends feel at a party. Introduce them to friends and be patient to explain stuff if they are not getting it right away.
After all, party is all about connecting people, isn't it? Don't leave anyone out!