Xu Xia likes Su Chen for a whole life, just because the young man at that time said: "I promise you to be pure and flawless for the rest of your life." Xu Xia's love for Su Chen is just like what is said in the book. When you are young, you can't meet someone who is too amazing, otherwise you will be a makeshift for the rest of your life.
This novel and its characters are purely fictitious. Any similarity is purely coincidental and should not be imitated.