This one could be for anyone attending a wedding. But if you are in the wedding party, you are spending a lot of time with the bride/groom. Do not stress them out with your drama, complaining, or critiques. This day is not about you. So whether you have beef with one of the other bridesmaids, or hate the color of your dresses, the bride does not need to hear about it or experience it in any way. You are there to support the bride/groom and be helpful, not a nuisance. So if it’s not necessary, kind, or helpful, then keep it to yourself.