During a party held at their house, Christiana is made well aware that her husband's friend has a crush on her and she's not going to let this opportunity go to waste. She makes it quite obvious that there is enough of her to go round, and the following day when she is enjoying some private time with her husband, it is very soon blatantly obvious that there's more than two invited to this gathering. It would seem that in this case, three is definitely not a crowd.