How do we get this guy off the mortgage, quickly and painlessly?

[Jared Polk]

I'm just getting started and am planning on buying a MF in the near future. I just met a potential money partner who own a 4br she lives at. She put her ex on the title and the loan is in his name. She has substantial equity and wants to invest with me but her ex (common law marriage) wants 250k to take his name off. She's thinking of giving it to him out of desperation but doesn't want to since all the mortgage was paid out of her pocket. She's thinking of trying to assume the loan but I told her I'd try to see if there is a better way to move forward. Any advice? Thanks!