This gal is being so nosy... Holy heck leave them alone. If she wanted to tell ya she would!
Also, the reason for Kei being alone at school gave me a thought. What if its that cliche where someone is isolated at school for being gay? Kei seems really friendly to get along with after all, so I can't see another clear hinted reason why someone like her would be alone. Though, if thats the case and Ruri figures that out its going to spell drama