Spoilers galore…tread carefully!
1. Xu Feng refusing to accept the royal engagement
The main pivotal point was when Xu Feng essentially pulled the old like-father-like-son move. He decided not to accept Jin Mi and Run Yu’s engagement based on his own feelings rather than what would be an easier path for Jin Mi. Back in the day, his father, the Heavenly Emperor also refused to let go of his love, the Floral Immortal, Zifen and chose to imprison her than let her marry the Water Immortal.
Xu Feng too had fallen in love with Jin Mi by the time her true parentage was revealed but Jin Mi at this point was under the influence of the Unfeeling Pill (Yun Elixir) and was content to go ahead with her pre-destined engagement.
He repeatedly misread her actions and assumed that she was expressing feelings for him. The results were some hilarious scenes like when he was showing off his closet full of mementos from past conquests to impress while Jin Mi simply thought he means to occupy an empty shelf with her head.
Had he accepted that she were to be his sister-in-law, Jin Mi would have been the same girl that she was, naive, innocent and she would have been in a comfortable albeit passionless marriage with Run Yu (since this was before he turned evil and she did like him as a friend).
2. The confrontation with Rat Fairy
This was a tough call for the Night Immortal and a serious speed bump in his wedding plans with Jin Mi. The discovery of Rat Fairy being a rebel gave the Heavenly Empress a chance to accuse the Water Immortal. He retaliated by declaring Run Yu and Jin Mi’s engagement void but Run Yu pacifies him by requesting to postpone the wedding by a year instead.
Even Xu Feng commended Run Yu on this close save but in time this gap of one year would prove to be fatal to his chances of getting a happily ever after with Jin Mi.
3. Xu Feng following Jin Mi to the Mortal Realm
I get it that when one gets to know their mother is getting the woman they love killed in an alternate universe, you jump first, think later. However the Fire Immortal could have protected Jin Mi better if he had remained …ehem… immortal (like the Night Immortal did). His breaking the rules by jumping in to the Cause and Effect Plate nearly resulted in Jin Mi being sent back to go through the process again!
He basically chose jumping off to another realm over having an uncomfortable conversation with his mother…well I guess there I can’t blame him. Once in the mortal realm the bond between Xu Feng and Jin Mi was so strong that it even weakened the Yun Elixir and the choice was made. Therefore while imprudent, Xu Feng’s decision paid off and truly felt like the moment when the scales tipped in his favor to win Jin Mi’s heart.
4. The meddling of the Moon Immortal
The most industrious wingman if there ever was would pale in front of the Moon Immortal. He is a great comic relief but creates some serious mischief. Using his magical red strings to connect Xu Feng and Jin Mi together in the mortal realm while knowing she is engaged to Run Yu may be edging towards tilting the scales unfairly. Also as the Moon Immortal isn’t he supposed to like the Night Immortal better…just naturally?
His biased intentions ultimately gave the added nudge to push the lovebirds towards each other. However this action might not have contributed to turning the tide towards Jin Mi choosing Xu Feng as much as the earlier ones. Once in the mortal realm, I believe their destinies would have gotten them together no matter who intervened.