Mostly, it was the fact that Sanae had only been in the relationship with Kogasa for a month, even if she's been friends with her for about two years. But yes, seventeen's a damn young age for talking about marriage.
Actually, that makes me remember something.
> Do we know how Kanako-sama feels about our relationship with Kogasa?
> "Well... um..."
> Sigh.
> "Kanako-sama, someone, a friend of mine, told me she, erm, liked me. In that kind of way. But she knows that me and Kogasa are, well, dating, and I don't really know what to do."