Fireflies can't get close to fire, and Liu Ying shouldn't meet Gu Yan either
"Are you willing to be your mistress?"
"What I mean is: I like you, will you be with me?"
…
"I wish you a bright future"
"If I had known it would be the last hug, I would have hugged him tighter."
Fireflies should not be close to fire, just like Liu Ying should not meet Gu Yan
The ending is be
Motto: Life is short, don't leave any regrets