Call in for backup a likely relative of the less than helpful photo subject if need be. If you are the partying type, this one might be tough on you. This is one of the best parts of the job, the people. It can help a lot to smooth things on the big day. You can tighten things up a bit by not shooting so much. One weekend I met an iron sculpturer who built the decorative trellis the couple got married in front of. Before the wedding, the happy couple is juggling caterers, flowers, tux rentals, family, etc… But after the fact, all eyes are on you.