A friend of mine is in a bind. Next week, she is supposed to participate in a friends wedding as a bridesmaid. She feels uncomfortable about this, because she knows the bride has been having an affair for the past few months, cheating on her future husband with a married man. She feels she has an obligation to appear at the wedding, but does not want to condone the brides behavior. What should she do?
The symbolism of standing in front of and family in a hideous bridesmaid dress as part of a wedding party is fairly simple: the bridal party stands up, or vouches for, the sanctity of what the bride and groom are about to do. If this is not something your friend feels she can do in light of the bride's infidelities, she should not participate.
Your friend should also consider how the groom would feel weeks or years from now if he finds out not only that his bride had been cheating on him, but also that her bridesmaids had known about it all along. For the sake of your friend's honor and as a consideration to the groom, Ask Gothamist recommends that she confront the bride and ask her to come clean.
Under no circumstances should your friend threaten to tell the groom, but she should not feel compelled to physically vouch for a relationship she knows is flawed from the get-go. This sort of condition - either you tell the groom or I sit out the wedding - will undoubtedly cause a great deal of friction in the days before the wedding but your friend should take comfort in the fact that she will either be saving a marriage that can be saved or preventing one that would only end in disaster.
Just make sure your friend isn't dealing with this bride.