If that's proof, I'm writing from an iskeai with internet access. I do agree that she regressed mentally, but this is no proof.
If you want to know how you prove that a character regressed mentally see https://mangadex.org/title/51376/reincarnated-as-an-aristocrat-with-an-appraisal-skill...
When I saw that 'heroine' I couldn't help but wonder if Japaneese girls are usually so mentally ill that they'd actually do this, or if it's just subpar-trash even for isekais. I guess it's the second. I guess I'll drop this.
So she is going to fall for him after he forced her to marry him? So cringe.
Not to mention that if she wanted him to leave her alone, she should have just acted like the original as he didn't have any interest in that type of woman.