Jiang Yi went to a nearby lake and swam around for an entire hour until the heat was released from his body. After that, he returned and told Wu Que'er to set off immediately.
Wu Que'er was the North Thearch's granddaughter, and the Wu Clan did kill his father. They had a deep-running feud, and Wu Que'er did almost kill him. For these reasons, he could turn Wu Que'er into his soul slave, kill her, or even torture her. However, Jiang Yi felt that raping her would cause him to lose his bottom line and his humanity.
If he did it once, he would do it again and again. If a person lost his bottom line and humanity, he would become evil through and through. He would lose himself and turn into a real demon. That was why he chose to run out and force himself to control his desires.
If a person failed to control his own desires, then this person would never be able to accomplish big things. This was what Jiang Yunhai taught him from a very young age.