Hi Sammy! I'm Katie and I play two girls here, though neither of them are blond.
This journal is Ruby Robins, seventh year Gryffindor and older sister of Demelza Robins. Their dad is a Quidditch journalist, so maybe Roger has heard of him. Ruby has zero interest in Quidditch, though. She wants to be a Healer when she grows up, but her favorite class is Care of Magical Creatures. She's a lesbian and has/had (I'm not quite sure...) a huge crush on Fleur, so if Roger noticed her staring at them during the Yule Ball, that's why. :P
I also play CHO! (seekingcho) who obviously knows Roger pretty well. Objectively she thinks he's fit, but dating him would feel a bit like dating a brother. She might still flirt with him though, at least when they're still single. Just a little bit though. Also, it's worth noting that Cho hasn't really played in that many actual Quidditch matches -- two years ago she was only a reserve, and last year she had tendinitis and was out until the Gryffindor/Ravenclaw match. She still thinks Roger is the best captain ever though.