Imagine Kai realizing after the merge that he has feelings for you. Before the merge, Kai knew he has some type of feeling for you, but he couldn't place what they were, he was comfortable around you and didn't have the urge to kill you as he did for your friends.
It wasn't until after he merged with Luke that he began to explore those feelings more, he even looked up on the internet 'butterflies in the stomach' thinking that he was ill, but his searches all came back to the same thing; he was in love.
❝Feelings are hard❞