I don't get what her hair has to do with this woman's wedding?
Why should she have to wear a wig? What is so wrong with her hair?
I think that this is on the same line as asking someone to bleach their hair for a wedding. Utterly ridiculous!
I actually knew a biracial woman (Japanese and Anglo) whose fiance asked her to bleach her hair for their wedding. She actually did it. If you can not accept a person for who they are...
It's not about her hair not being ok as it, it's about the bride wanting a certain look for her wedding. I was in one wedding where a bride wanted everyone to wear updos....not my usual look, but that's my girl, so I did it. It's just one day. It's just hair.
So, OP - you have to figure out what's more important to YOU, selecting your own hairstyle when you're a bridesmaid or being in the wedding. Good Luck no matter what you pick!