What is the relationship between Feng Ye, the grandson of Tianyuan, and the protagonist?

Marriage. According to the information of the novel Tianyuan, in this novel, the protagonist Chen Qingyuan strayed into the forbidden area, lost all his martial arts, returned a hundred years later, and was confirmed as the marriage partner by his eldest grandson Ye Feng. Because Chen Qingyuan didn't understand the present situation a hundred years later, he followed suit and became the marriage partner of his eldest grandson Ye Feng, so they got married.