This one kicks off with an intriguing situation. Viola's stuck in an engagement with a guy who's just short of being hostile to her, but who won't dissolve the engagement. When she gets knocked out in an accident, she realizes it's a chance! She's going to pretend she's amnesiac, remembering nothing and useless as a partner, to get their families to call off the engagement. Except that when her fiancé learns of her amnesia, he turns into a completely different person, and starts making up complete lies about what their relationship was like. Just what is going on?
However, this pretty promising opening gets buried under a pile of total blandness. Nothing really stands out - not the characters, not the situations, and not the resolution either. For instance, the heroine: I don't think we learn a single thing she's actually good at over the course of the book. We learn about stuff she's terrible at, like cooking, baking or embroidery, we see her do some hobbies like reading, but we never see her being actually capable at, well, anything. She doesn't have any job or a responsibility, she doesn't even go to tea parties or soirées. Beyond talking to her fiancé, talking about her fiancé, or thinking about her fiancé, she doesn't have anything in her life. "Cute" is probably the most specific positive quality anybody attributes to her in the whole book. So utterly bland.
By the way, I'm starting to suspect there must be some kind of rule to light novel romance that gets strictly enforced by the light novel police. What the rule most likely says is that anybody who understands a situation the protagonist doesn't must keep a total silence about it, for reasons. Only once the protagonist goes through all the work needed to figure out the situation for themselves are others allowed to reveal they actually knew all along. And that's how you get people letting their friends struggle through a decade of misunderstanding instead of, you know, dropping a hint or two.
Sigh.