Why did one direction break up?

It really came down to exhaustion. For five years, their schedule was relentless. They were constantly touring, recording, and promoting. It was just non-stop. Zayn leaving the year before was a huge factor too.

Ultimately, they all wanted to explore their own music and have a chance at solo careers. The official line is that they're on an "indefinite hiatus," not a permanent split. So, it was a mix of pure burnout from a crazy pace and the natural desire to grow as individual artists after being in a group for so long.