A common trope in romance is the extravagant gesture: the wealthy lover/caregiver does something over-the-top for the beloved.
The Little Princess uses this trope when the wealthy gentleman refurnishes Sarah's bare attic room overnight. In all fairness, this moment in literature/movies is quite touching, a eucastrophe, a light at the end of the tunnel.
In love romance, however, the trope has its problems. Whenever I'm watching a drama and the romantic partner does something over-the-top--rents out an entire restaurant for the evening; buys up all the plushy toys in the store; whisks the beloved away on a vacation to another country--my thought is, "Wow, what would you do if you didn't have money? Would you even have a romance?"
Dorothy Sayers would point out the immense sense of obligation created by the so-called romantic extravagant gesture.
Can/Tin come out ahead here (again, the writers on this project truly appear to have known what they were doing, at least with these characters). The characters avoid the money=love implications of the gesture as well as the money=the-only-way-I-can-tell-you-how-I-feel-or-that-you-will-acknowledge-how-I-feel recourse, which mindsets spell death to the future day-to-day relationship. A few scenes/events stand out:
1. Can's refusal to accept gifts (except "yummy" snacks), which leads to the scene in season 2 when Tin tries to convince Can that his phone was run over by a truck, so Tin could buy Can a new phone and get Can's number. The attempt is funny, mostly due to body language, and it backfires. Can determines to pay for the new phone in installments.
2. Tin's car. Most indicators of Tin's wealth are attached to his car. It is a great car (and I'm not a car person) and deserves its own photo opportunities.3. Tin actually works for his money--he doesn't just "have" it. By the end of the series--when Tin moves into his condo--he is attending school and working for his father. He doesn't go abroad only to fetch Gonhin, his brother's lover, but to do something real estate-related for the family company. The money is inherited--it is also earned.
4. The sweetest gesture in the series occurs when Can gives Tin the small cake. "I love you a lot, you know," he says, then sings the Happy Birthday song (which is far more ubiquitous than I ever realized) in English. And Tin appreciates the gesture.