question..?

ok, so you know at the end how they're talking about the wedding and everything? and the stepmom says something to the grandma about how she's gonna look so good in white? and everyones like noo! not white! so she's like um okay?! peach? and everyones okay with peach instead. Did i miss something during the movie?! i've never gotten that part. how come none of them want white?