My sister is getting married in a spooky Halloween ceremony wearing black next October. I've seen a lot of people negatively react to her desire for her and the groom to be the only ones wearing all black. I know she wouldn't be getting this reaction if she was wearing white. Everyone would steer clear of white except for shirts under blazers and other minimal stuff. After getting this reaction, she feels even more nervous about mentioning that she wanted to do a theme.
I feel like it's completely acceptable for her to suggest the theme and that no one wears all black. No one gets upset when the bride restricts your dress in a traditional sense. Any opinions or advice?