If you've been making all your payments on time, you should renegotiate the loan and take him off of it. Assuming your credit and your girlfriends credit isnt shot to shit, you should be able to negotiate fair terms. Just take a slightly higher interest rate.
The problem is, if they find out he went bankrupt, and you didnt tell them, they'll definitely pull the loan. BUT, you can play the chance that the information will never come around to them and you can continue making your payments happily. Just never be late.
