Why Not White?

My mother-in-law wore white to our wedding. Head to toe, dress, stockings, shoes. She told me she was going to wear burgundy! I was insulted, that she wanted to be the bride. I tried to explain this to my husband, but he doesn`t see it, does anyone have another way tosay it? What meaning does it have? I need some info for my position. Which colors are off limits, so I don`t offend anyone by accident.