Because you are going to be related to her for as long as their marriage lasts, do you think it would help to speak up? Have you asked her if you could be in the wedding party, so someone from his side of the family was represented? You could wear her colors and be greeting people at the door or offer to be a female usher for your side of the church, if not a bridesmaid. It is important to approach it from the spirit of family unity, and not set up for a fight if she says 'No'. If she does, just say, 'I wish you felt differently, but I know it is your wedding.' At least it will be out in the open, and your brother will learn something about her. If you stew about it, it could make all the family events in the future awkward. I understand your pain. I was invited to my nephew's wedding when I was fat and the wedding album came without a single picture of me. I spent hundreds of dollars flying there, having a dress altered, and staying in a hotel, and no one would know it from the photos. I was in pictures taken at the wedding, but the ones they chose for the album didn't include me. Even a family picture of our side of the family must have been taken when I was in the bathroom, because I am not there. The bride had the nerve to ask me to buy some of the pictures, since it would reduce the bill from the photographer. My sister (his mother) and I have never had the same relationship since this happened. I wish I had expressed how I felt, so it was out in the open and I wasn't still hurt by the memory. They split up after a few years, and everyone probably threw out the albums, but the hurt remains. I hope she reconsiders for your brother's sake and for all the future family events this will affect.