暖她一整天

Meaning

The "three characters" meme comes from clickbait titles often used by marketing accounts. "Guys who say these three characters before bed are so hot", "Basic girls say goodnight, high-EQ girls say these three characters" - click through and the content is garbage. So everyone started mocking this phenomenon - whenever mentioning something romantic, just say "three characters". Don't worry about which three characters!! It's just "three characters".