Kyo and Tohru are meant to be. You all should have notice it. She is definitely dedicated to the cat spirit/Kyo and as the story goes on, they will definitely realized they are falling for each other.
Huhuhu the part where his true form was revealed. He was probably afraid that if Tohru saw other form, she would leave him and at that time he thought it was over for him. He didn't want to lose Tohru.