Hard to say. A lot would depend on the themes, art style, and how well the relationship is portrayed in the manhwa. Sometimes it could be a yes, but other times, not so much.
The reason could be anything from a romantic encounter gone wrong to a mystery that needs solving. Maybe it's part of a larger conspiracy or just a random act that leads to unexpected developments in the story.
There could be multiple explanations. Maybe it's to protect someone or achieve a greater goal. Or perhaps there's a misunderstanding that's led him to act this way.