Their relationship began like a storybook high-school romance: a prom date, love notes, sneaking off to be alone. But unlike other kids at school, they had to keep their dating secret, because their parents disapproved. Both of them, but especially Adnan, were under special pressure at home, and the stress of that spilled over into their relationship. Eventually Hae broke up with Adnan. And then, depending on who you ask, Adnan was either understandably sad and moping around, or full of rage and plotting to kill her.
If you're just landing here please go back and start with Episode 1.