My son purchased a home with his then girlfriend......they subsequently broke up and he signed a quit claim deed.

Your son exercised poor judgement in making a substantial purchase with someone without having a stable commitment to and from that person.  He exercised poor judgement again when he conveyed his interest in the property apparently without getting legal advice.  As a result, he has a rather serious problem. By signing the Note and Mortgage upon purchase of the property, he committed to the lender that he would pay the Note amount according to a specified payment plan.  The lender is not concerned with whether he has continued to own an interest in the property or whether he might have conveyed his interest to the other co-owner.  The lender will expect to be paid and, if payment is not receive, the lender will almost certainly foreclose on the loan and, if any deficiency results from a resale of the property -- that is, if the lender does not receive full payment in the foreclosure process -- it will likely sue either or both of them for the deficiency.  You son should hope that the property can be sold on the open market and that the mortgage will be paid in full.  That is the only way he will be relieved from the debt.