Several people wore black to our wedding. I guess it's ok but I would have liked more colour. The mother of the groom could wear dark blue which also looks stunning with silver accessories. I guess I'm not a fan of black for weddings.
The groomsmen and my FH will be wearing all black with coloured flowers matching the bridesmaids they are matched with. Black seems to be a common colour these days. Thanks for sharing about the colour red in Sweden never knew that.
I say wear whatever you will be comfortable in and not have regrets with when looking back at photos. There are so many traditions nowadays, so unless the couple has set a specific dress code I say go for it!
I think it's totally fine, but more so if it's an evening or winter wedding. It's sometimes hard to find fun, flattering dresses that are still appropriate in colder months. Plus not everyone feels as confident in colour.
I think it is ok, I would not think the person wearing black was protesting or in mourning. Black is classy and easy to wear, most people have black already in their wardrobe, especially for very formal weddings. If the style of the dress is appropriate to the wedding then I think it being black is fine (no long black dresses on the beach, for example). Personally I'd try to avoid it but if I couldn't I'd be sure to wear bright shoes and accessories and either a colorful cardigan or wrap.
Have you seen the black dress she is planning to wear? Are you having a formal or black tie wedding? Do you think she is trying to send a message or does she just like the dress?