Here's what I hear:
Girlfriend was close to dad,
Girlfriend lost dad,
Losing her dad throw all relationships off balance,
Girlfriend was trying to sleep (much needed sleep) when room mates started to fight ,
Girlfriend got scared,
Girlfriend felt ganged up against when telling you she needs a more peaceful living arrangement,
Girlfriend feels worse because since you weren't listening she would have turned to dad but she can't.
So now your relationship is more shaky.
_______

She needs a more relaxed living situation that she feels safe to deal with her grief in. Instead of investigating a cheaper smaller place you outright said no without understanding how hard this whole situation is for her. The fact that she moved out of her own home should make you step back and investigate what's really going on. Yes it could be bipolar or she could feel unsafe whether actually physically or to grieve. She needs to know right now that you are there for her even if it's not monetarily possible. I would suggest going to stay with her until you guys find a place that can be just you two. Even if it's closet size. Try to get her and yourself into therapy so that you can deal with this the best way possible.