White Jade of Sunset Mountain
I wonder if he fell in love with her so he gave the stone his soul instead to replace hers. This is what I think because when he started to wither, it said he screamed mournfully. It could just mean that he didn't want to die, but I take it as mourning that who she fell in love with, was her husband and could not reciprocate his love even if it was he who "consoled" her by taking her husband's form. Also, her "husband" kept telling her to not come back, as if he was trying to keep her from mourning and to "set her free". In the end, he gave up his soul for hers. This is just how I take it.