Learning
Afterward, they realized there was much they did not about each other. Not necessarily big important things but little details.
Gwen learned that Arthur did not always snored- when positioned his stomach, he was quiet. Arthur learned that Gwen, while a resilient person with few fears, was rather uneasy around centipedes. She soon learned how he 'disliked' spiders.
They both knew how to swim (and quickly found out that together in the lake during hot summer days were pleasant). They both knew their letters and numbers - Arthur a typical stern tutor able to withstand his energy and Gwen was mostly self-taught until Morgana decided to have her learn more so to help with her lessons (particularly arithmetic).
Arthur learned of her infatuation to Merlin and Gwen learned that Arthur was the jealous type. He learned that she did not like onions due to their odor and loved wild lilacs because her mother used to place them on her bed every night.
Her mother died on a Tuesday night after a taken ill by a plague that swept Camelot years ago. He had a dog named Grach that was killed by a boar.
They learned much and their love grew stronger. And after they wed, they learned that no matter what, they will have each other.