He saw her walking down the aisle in her white dress. Her golden hair was decorated with flowers, the same flowers that had graced the garden of the Houses of Healing. The first time he had came back to her after telling her that he had loved her, he had plucked one of those flowers from the bushes and placed it on her hair.
Now on their wedding day, she was wearing those flowers, not only in her hair but on her wedding gown as well. In fact, her whole persona seems to glow. Perhaps it was the pains that she had to sit through to look good on this special day or the smile on her face. Either way, she looked happier than she did for a long time.
He realized the cause of her joy and he understands. For he is happy as well.