"Since you let Tom get away, I guess James makes a good runner-up for happily ever after!" Ouch. Talking about exes at weddings should always top the list of restricted topics.
You never know what kind of offhand comment about a blast from the past will stir the pot. Those innocent comments about your gal pal's former beau being better looking and making more money? Looks and cash could be sensitive subjects, and you don't want to be responsible for the newlyweds' first married argument.