My girlfirend is pretty terrible with her credit, and has almost no concept of money. When we first got together she mainly had store cards and a low limit Wells Fargo visa that her parents had set up years before and charged gas to to show activity. When she graduated from college two years ago she applied for the Alaska card to buy plane tickets as one of us travels back and forth between states every 3-5 weeks while I finish school. Recently she recieved a letter from WF stating that they'd raised her limit from $1500 to $3100. I thought that was a sign that she had been taking my advice to heart. We'd had a discussion back in March about her finances that ended muddled but she'd acknowledged her shortcomings. Well, we were at the grocery store the other night and her cards were declined. Turns out, her Alaska card is sitting at 113% and Chase has cut her off in anticipation of an impending default. WF is used to her maxing out the card and I probably won't seek AA, but she's sitting at an aggregate 82% utilization across all accounts and I don't want BoA or Chase to close/balance chase her.
I figured I could add her as an AU on my Discover card which would just about double her total available credit ($13.1k -> 25.1k) and help bring down her utilization as Disco is my AZEO account with a routine 1% statement balance. I thought about the Chase card, but am cautious about giving Chase any leverage over me if they see her on my account. Is there anything else I should be cautious about? She won't have the card and wouldn't use it anyway.
@Anonymous wrote:Adding her as AU is putting lipstick on a pig, for lack of a better term.
Even with your AU account, she will still have maxed out cards which have the worst effect on FICO scores and will spook lenders.
She needs to attack her spending budget immediately, work extra hours or gig economy jobs, and pay it all down to $0. If she can't do that, be cautious.
+1000
This is her chance to change her habits. If I were in your shoes, her getting her financial situation and habits healthy would be a requirement for ever taking the next step of either living together or marriage. I've dealt with too much crud in the past to be soft on these things.
I have a family member that has always struggled with credit-related issues, always ducked creditors when payments weren't made, filed BK years ago, and I just found out there are charge offs and collections on current credit reports. I've offered to help (clean up reports, NOT monetarily) many times, but will not lift a finger until I see effort and desire on their part. In the past, parents and others have bailed this person out over and over again, reinforcing the bad habits.
I guess what I'm saying is don't enable a pattern. Sometimes people need to learn the hard way, and if you soften or prevent the fall, you could get in the way of that learning. And then there are people that will never change no matter what. I hope that is not your girlfriend! 
@Anonymous wrote:
If I may suggest not adding her as an AU until she pays off the debt. Adding her as an AU only enables her to continue these bad spending habits, not deter them.
You stated her utilization was at 82%. For a CL of about 13k, that is over 10k of CC debt. Adding her as a AU may enable her to stave off AAs, but more likely, it will only serve to give her room to get further in debt.
It seems your heart is to help her, but unintentionally, this may do the opposite.
Yes! in a creative way if she is able to pay down her debt 50,$100 not sure what she could afford but it would help to also show you the actions of understanding your heart is in the right place no doubt but she could help the both of you in the relationship so then if you wanted to help it's not just you both the two of you working at a much larger goal of getting her back on track. 
Thanks for all the input! I definitely won't be giving her the card in order to limit my exposure--not that I believe she would use it anyway. We'll be looking at housing in June after I graduate and I figured any boost possible to her score now will be better than nothing. Turns out she never even thought about interest and I showed her what 19.99-23.99% APR means. So far she's put an extra $1,000 towards her bills this month.