Ok, so I have a friend who was not married ,but, lived together with a gal for five years.?

She basically left him or abandoned him. He decided to buy a house and she helped a s a co signer and by the time she had a job so it was just right. Now that she is gone I'd like to know if he would in the future need to sell the house to give her money even tho she hasnt helped with the payments or if he can take her out of the loan??Thanks in advance