What would you think if your girlfriend told you she wants to move in with her mother because she uses most of her money on bills. She also tells you not to be angry. 

that shes not ready to be a responsible adult and if she does not start now she never will be.

its hard at first for everyone to live with no parental support it took me ages to get used to it but, once i did i never wanna go back.

I would think I just got dumped.

I would tell her I "understand", then the second she leaves invite my boys over and have a small party.

You really don't want girlfriends like that in your life.... she's gonna be even worse if you ever put a ring on her finger.

this, but what age if shes under 20 maybe maybe its okay also how long are ye living together

I guess it depends on the culture she came from. For my own culture it's only the lowest of the low that move back in with their parents, but for my girlfriend it's expected that if anyone is having a hard time they can always move in with their other family members. If that's the case for your girlfriend then this truly might be just as she stated and she needs to move back in with her mother to help with bills, but if not I'd think I got dumped.

Also, a question, does that mean you now have twice the bills to pay?

Tell her to fuck off because she doesn't want to be responsible enough to pay for the bills. If shes doesn't want to do it now she won't in the future, dump that goldiggin ass

It wouldn't be strange to her parents if she mioved back in. The only problem is her family treated her like ass before she left and it strikes me odd that she would even consider it.

The idea that she is giving me is that she using virtually all of her money on them. We live in a house together with my sister, we pay the morgage. i am a poor college student and I struggle the hardest to pay the morgage/bills ect, but I would NEVER consider going back to my old place. It's a nice house and we are lucky to be so young (all of us are in our 20's) and pay for our own house, with low morgage as well. 

She has "changed" her mind, but I am now deeply disturbed about the situation. Came out of left feild.