Is there something wrong with my roommate/friend?

If she is your friend, you should definitely talk to her. Just kindly sit her down and explain to her that you don't know why, but she has seemed distant lately. You should also talk to your other "friend" who gossips about her and tell her the GROW UP; talking about others never benefited anyone. If money is tight, she could be stressed; we all know money problems will do that to you. Like I said, the BEST thing you can do for her is to have a heart to heart. Maybe grab a bottle of wine and ask her if she wants to have a movie night; just the two of you...like good old times? A little wine will help her to open up as well. Good luck!