He was getting married to someone he really loves. She was getting married to someone she really loves. But ... none of them know, that someone they really love also love him as much as she loves him. They share great amount of love since they were in diapers. But as young adults, when he showed her greater amount of interest, this person didn't do anything and stayed silent. This person afraid, that if she said more, it will broke the bond they share for years.