The problem is Chiaki's lack of romantic awareness.

You consider the problem at hand. Chiaki's lunch, as far as you can tell, had been smooth sailing towards her continued contentment. She certainly seemed to enjoy the company of this Hajime, who sounded like a decent young man, but she'd failed to pick upon his offer of a date and rejected it so callously, one could think it malicious.

Of course, you know there's nothing like malice behind it, and you have a quick way to prove it. "Chiaki," you address your patient. "Do you think Hajime likes you?"

"Yes," she mutters, sleepily. "I don't think he'd spend time with me if he didn't like me."

"Naturally. But do you think he's interested in you romantically? In becoming closer with you and furthering a romantic relationship with you? Answer honestly: you won't need to worry about this conversation at all later on, and all your secrets are safe with me."

"... I don't know," she replies after some hesitation. "Maybe, on some level... I think I recognized he was offering me a date. But I didn't understand the point of it... so I answered honestly..." she mumbles, beginning to slouch to one side.

"I see. And are you interested in a romantic relationship with him?"

She hesitates briefly, looking lost in thought for only a second. Of course, it ought to be her subconscious answering directly, so the only reason for the delay would be genuine difficulty in reaching an answer. "I really... don't have any idea how things like that work... So, if it's fun being his friend... I'm afraid to try to be something else and mess that up. It's like the random reward option... if you pick it carelessly, you can lose your whole run. If you don't understand the game completely, it's too risky..."

You shake your head, gripping your knees and facing Chiaki intensely in spite of her entranced state. "That's wrong, Chiaki. I'm sure that an unpredictable romance in this, the prime of your youth, is exactly what you need to live life to the fullest and maximize your happiness! As your therapist, I strongly recommend it! Won't you regret it if you let it pass you by?"

"Maybe," Chiaki mutters noncommittally, yawning even though she ought to be in a trance. Her mind, somehow, seems to be wandering. "You know, I read some people are 'aromantic'... Grayromantic? Demiromantic? I remember reading about them, but... not what they mean... But when I read about them, I thought... Maybe I'm like that?"

You pause. Your patient has clearly thought about this more than you expected. It turned out it wasn't fair to say she lacked romantic awareness. Maybe it wasn't that Chiaki didn't care about romance, but that she genuinely couldn't feel it? The average therapist would probably slow down, consider this carefully, better research and consider a topic he didn't fully understand...

You clench your pen and pad in your hand, then toss your tools of the trade aside, meaningfully. You're no average therapist, dammit! You're the Ultimate Therapist! Your power makes it so you aren't limited by the ordinary boundaries of therapy, boundaries that can make the patient suffer for years before reaching a stable, manageable condition. You can maximize Chiaki's happiness, and you can do it now! If you have that capability, don't you owe it to her?

You won't falter on your principles. There's no question of what you must do: you need to guide Chiaki on the path that takes her to a fairytale ending that brings her happiness with the young man she likes... Or might like... Ought to like? Whatever! The real question is how to achieve it.

But how do you teach a person to love? Can you just say "whenever you feel a romantic impulse, act on it?" How do you do that when the patient doesn't even understand what a romantic impulse feels like? Even hypnotism only goes so far... What you need is some method to rapidly provide a framework, scaffolding to help Chiaki build an understanding of what a romantic relationship is and why she should want one. What's the best way to teach her?