Helping Out A Friend?

Matchmaking.

Red string of fate.

Destined partners.

Xue wasn't a god of anything but he knew how things operated to some extent due to the fact that he served underneath the Moon Goddess Chang'e. He encountered Sun Wukong before, the Monkey King. And he almost managed to sneak into the Celestial Banquet a few times before. The Moon Palace was a lonely place, but it was also a place that held knowledge about the affairs and jurisdiction of the gods.

Yue Lao.

The matchmaking god for couples between man and woman.

Tu'er Shen

The matchmaking god for couples of both men and women.

Predestination. Did he believe in such a thing? Well perhaps he did, but then again, humans were always going against their own fate. Capable. 

Not only humans. Xue had to be more specific. Defying fate. Anybody could do that.