Two male leads, older man and younger man, not each other's firsts, happy ending (though there is heartbreak), some school scenes, a long timeline, limited writing ability, few sci-fi elements, please bear with me. Please don't break up the official couple; I ship the brothers.
Gastroenterologist × junior high math teacher
Chen Xiyan × Mu Chi
He was the new student who arrived in the second year of junior high with his hair tied in a ponytail, always silent, and just as quiet when he left.
Fourteen years later, they meet again. Over the course of fourteen years, he mends your wounds and slowly draws you out of the darkness.
I hope we meet, know, and love each other countless times on a Mobius strip. I will save you without hesitation, again and again, my camellia.
Theme: Fate cannot be defied