One possible plot could be that Naruto is hypnotized by an enemy ninja who wants to use him against the Hidden Leaf. Ino, being a skilled mind - user herself, tries to break the hypnosis. She has to first understand the nature of the hypnosis, which might be a complex jutsu. Then she dives into Naruto's mind, where she encounters various manifestations of Naruto's fears and desires. Ino has to navigate through these to reach the core of his mind and free him from the hypnosis.
Often, Ino is initially shocked. After all, Naruto might not be the person she expected to ask her out. But then she might show her kind side and accept. For example, she could blush a little and say yes with a shy smile.
A rogue ninja from a neighboring village could be the villain. This ninja might have a vendetta against Ino's family and uses Naruto as a tool to get to her. He hypnotizes Naruto because he knows Naruto is strong and his actions while hypnotized would create a lot of trouble for Ino and Konoha.
One possible plot could be that an enemy uses a new jutsu to hypnotize Naruto and then makes him target Ino. Naruto, under the hypnosis, starts acting strangely towards Ino, which causes confusion among their friends. The story could then revolve around how their friends try to figure out what's wrong with Naruto and break the hypnosis before he does something really bad to Ino.
Naruto might react with shock at first. After all, his whiskers are a very distinct part of him. He could then start laughing it off as one of Ino's crazy antics. He might even joke about it and say something like 'Hey, Ino! Those whiskers are my trademark!'
I think Naruto would be heartbroken. He's always been so open and sincere in his feelings. When he discovers Ino has cheated on him, he might go on a bit of a self - discovery journey. He'd wonder what he did wrong, even if it wasn't his fault at all. He could also become a bit more cynical about love, which would be a big change for him. He might start to see the world in a different light and be more guarded in future relationships.
She might be initially shocked. Ino is used to Naruto's regular abilities, and the sudden appearance of the Rinnegan would be a huge change. But then she would probably be curious and eager to learn more about how it affects Naruto and what new capabilities he has.
Ino might be initially shocked. But then she'd probably be quite excited. She could start planning all sorts of things to do with Naruto, like shopping for new clothes or teaching her about girl - only ninja techniques. Ino would likely see it as an opportunity to have a new kind of friend.
Naruto would be extremely worried. He would likely call on all his training and skills. He might start by retracing Ino's last steps. He would also be thinking about all the times Ino has been there for him and the village, which would fuel his determination to rescue her. He would be so focused on finding her that he would hardly rest until she was safe.
Naruto might be initially confused. He's used to people being friendly, but Yandere Ino's possessiveness would be new to him. He could try to talk to her to understand what's wrong. But if she gets too extreme, he would probably be a bit scared and try to distance himself.