Kuafu chasing the sun means Kuafu desperately chasing the sun. It is a metaphor for people who have great ambitions, and also a metaphor for people who do not know their own abilities.
Jiang Yan is chasing Jiang Yan, another version of herself.
After meeting him, Jiang Yan discovered that I could live like this too.
In this love, I become a better person because of you.
If you can't get the same better thing, then I hope you won't be in this love.