There was so much that could make a man run insane, but In-Ha was quick to realize that all he needed to be admitted to an asylum was Lee Ni-Na and her devastating ways of evading him.
Frustration had never felt so close and real till he realized how insanely in love he was with Ni-Na, and how resolute he was in getting her to be with him forever. And that goal wasn't going to change even as she evaded him all through out the wedding rehearsal, and had chosen to surround herself with the company of familiar and unfamiliar men, much to his annoyance.
She had come in the company of her friends, and she was being too chummy with the florist, who was there on Dan-Han's request. The man was bent on making everything perfect for his wife-to-be, and he could see himself doing the same for Ni-Na. He'd give her the perfect wedding she could ever dream. That's what love does to a man.