You should always remember people's names at your wedding.
Emma is standing in the receiving line at her wedding when an older lady walks up who Emma doesn't immediately recognize.
Emma wants to greet the woman.
Emma thinks back to who she invited, realizes that the lady is her mom's friend, Joan, and greets her by name.
Emma asks the lady what her name is and then thanks her for coming to the wedding.
Joan is happy to speak with Emma and has a good time at the wedding.
The lady is upset that she came to the wedding and Emma doesn't even remember who she is.