What changed? I am hoping to buy out my W too. If you really want to do it, are their retirement or other assets you can give up to "purchase" her equity in the house?
If it is because you can't afford it, what are you basing the value of the house on? Is it an actual offer to purchase your house? Or is it just an assessment or real estate appraisal? For me, I don't think I am going to rely on any value other than an official offer to purchase, unless the appraisal comes in really low.