It wasn't as if he thought of her as a fool.... just incredibly naive in her own power. He had seen it before - he'd gone to school with the girls who had rather famously been known as the Hogwarts Hussies. Women who because of the presence of magic in their lives thought they had had more power in society then they unfortunately had. He knew times were changing but at the end of the day she was a young girl and as such she was just powerless in so many ways. It was the reason chaperonage was so important. Polite society be damned there were many questionable people out there who could take advantage of naiviety.

She was probably a girl who was probably born into a good family who allowed her her own rights and helped her stand by her choices but left her protected but that protection had left her so very, very naive. 

It was somewhat comforting that she had expected a courtship, though it did not change how he thought of her. A courtship involved limited contact and it was quite easy to pretend to be something other than he was at such a time and after they were married it would be too late for her to change her mind without enduring divorce. Additionally she really must think highly of her connections and determination. Did she really think such methods were infallible? His own owl had had trouble keeping track of him when he'd been on the continent and that had been when he'd been making no real effort to hide information about himself.

He'd had lovers, both male and female, whom had gone to extraordinary means to keep their affairs hidden.

He very much doubted such a young girl had the means or determination that such people used let alone the ability to investigate such people if she ever came across any of them. She was naïve. He wanted to take her in hand  and tell her that there were bad people in this world, and even in Hogsmeade, that had gone to significant effort to hide their true identities, and personalities. Perhaps he did underestimate her but he doubted it.

"I wouldn't call you a fool, Miss......." He trailed off, frustrated at his lack of knowledge but instead of leaving the sentence to open for her to introduce herself he continued. "But I do think you are incredibly naive in this matter.  No doubt I would be surprised with what you think you could find using your determination and connections but unless you are particularly skilled in this area I would think that you are  incredibly naïve to believe that that is a complete picture of anybody.  And now I don't know how old you are but I would say you couldn't be more than eighteen - I have female friends who are older than me who have yet to marry and whom are still considered quite eligible. So unless you have a specific reason to marry young I'd suggest not dooming yourself to a, now how did you put it, a good standing marriage on paper, and instead take the actual time to get to know somebody. You may surprise yourself and who knows you may even develop a romantic interest in somebody." He looked at her and couldn't resist adding to quote her.  "Or at least somebody who you would not mind to throw parties for or allow near the bedchamber"