Sangheon Lee birthday tribute: Why the XO Kitty star is one of Netflix’s most refreshing, charming rom-com leads

If there’s one scene that still sears, it’s when a gaunt, emotionally battered Minho (Sang Heon Lee) tells Kitty (Anna Cathcart): “We’re done.”

In a series that often glows in the brightness of romantic comedy, XO Kitty season 3 delivers one of its most emotionally brutal breakups. Kitty’s voice trembles, while Minho looks hollowed out, drained in a way we haven’t seen before. Lee, who has always relied on subtle expressions and controlled stillness, lets something raw break through here.

The argument isn’t just about broken trust, though that plays its part. It’s about emotional exhaustion, about the point where care curdles into resentment. For Minho, the real fracture is more devastating: what happens when someone you trust, doubts you, even though you did your best?

It’s a sharp contrast to how we first met him in season, flipping his hair to Hot' staring down at Kitty with a clipped “No English.” The introduction established Minho as one of Netflix’s most instantly recognisable teen characters: sharp-tongued, self-assured and almost theatrically self-contained. But even then, Lee allowed glimpses of something softer underneath, the loneliness of a boy living away from his mother, chasing a father’s approval. He masked need with sarcasm. As we realise slowly through the seasons: Minho has never had a 'safe space', or anyone to believe in him so strongly as Kitty does. And so, when Kitty doubts him, his entire system is rattled.

That tension of finding a space has always simmered in Minho. His humour is a defence mechanism, his confidence a performance. Early on, his vulnerability leaks through in unexpected places, like his hurt over not knowing the truth about Dae and Yuri, or the way he remains protective of Dae even while suspecting Kitty. Lee never lets him become just the comedy in a love triangle; he gives him weight, even in his most reactive moments.

As the series progresses, that emotional layering deepens. Minho’s heartbreak over Kitty calcifies. He tries to outrun it, even entering a relationship he knows is more distraction than cure. But it catches up with him in moments that cut through the humour entirely, like when he finally admits: “It’s bad enough that you broke my heart…”

By season 3, that accumulated history shows. Minho is still sharp, still quick with a retort, but the edges are dulled by something heavier. Responsibility, disappointment, and emotional fatigue sit beneath the surface. The character hasn’t changed completely; but he has been worn down in recognisably human ways.

That evolution is a large part of why the show continues to resonate with its audience, even amid criticism. Perhaps that's why the 'Mooncovey' fandom is so popular. The esonance comes from the chemistry between Lee and Anna Cathcart, which is an easy, lived-in dynamic that translates convincingly on screen.

Outside XO Kitty, Lee has already shown range in projects like Secret Ingredient, where he plays Junho, a character carrying a different kind of emotional burden; a more fractured one. In one particularly charged scene with his father, that tension finally spills over in visible, unguarded grief.

It’s still early in Sang Heon Lee’s screen career, but there’s already a clear pattern: He excels at characters who feel emotionally restrained until they aren’t. With more roles like these, he is likely to move far beyond breakout status into something more sustained.