You can’t make a guy show interest in you when he’s not interested. And I don’t think your guy is interested. He certainly doesn’t act like someone who wants to date you. Forehead kisses? Those are for little sisters and dogs.
What made you think he was into you in the first place? The flirting and compliments? Perhaps you have read too much into them. I think if the guy was into you, it would be totally obvious. You wouldn’t have to guess, and you wouldn’t have to ask how to make him act interested. I’m sorry, but this one sounds like nothing more than a friendship to me.
Thanks for the question.