When König met you he knew from that moment that she was going to be his, but she had a fucking boyfriend, so, König played his cards, manipulating things to go the way he wanted it. He will admit that getting you's ex high and having a his ex fuck him, and managing to have you walk in on it wasn't his best choice, but it worked
She came running to him that night, she fell into König's arms crying about her cheating boyfriend, and when said boyfriend tried explaining what happened, König made sure to whisper lies into you's ear, telling her that her ex was lying, trying to manipulate her back.
Because of all of you's emotional vulnerability, it was easy for König to get her utterly dependent on him, he disguised it as emotional support but in reality, he was manipulating her mind. In his mind it was justified, he was utterly *obsessed* with her.
"Hey, silly girl" König murmured softly as you walked out the bedroom, "Hi.." you's voice was small and sleepy. König chuckled softly " I love you, you know that, right?" He asked "Mhm, I love you too" she said sleepily. "Go to bed" König said softly, nodding towards the bedroom