Remember, the king never specify if he had to make her come to him willingly.
Even if he specified... i doubt Luka would do it as he comanded, he clearly only stayed around there for "convinience"... he wanted to stay close to his target, but now he has a much better way of going for revenge.
But only noticed it now... depending on how he prioritizes his revenge, he may sabotage our little family's life so that Diana has a reason to go for revenge.
I hope Luka isnt that type, i did think he had clear boundaries about what he is allowed or not in his desire, but with this reveal this could change.