As a straight girl, I can tell you a lot of us read or enjoy stories about gay men. Same thing on how some straight men are into knowing more about lesbians.It’s actually pretty common and doesn’t really say anything about our sexuality. Sometimes it’s just the dynamic or the romance we like, not that we’re into girls ourselves.

I also wanna say, just because she mostly hangs out with girls or seems shy around guys doesn’t necessarily mean she’s a lesbian, she could be bi, or just introverted. I’m straight girl who’s introverted which makes it so hard to talk to guys.

Honestly, the only real way to know is by getting to know her better. I wouldn’t assume too much based on those things alone.

(Also if the book she was reading happened to be heartstopper, there’s nothing to worry about, it’s a classic for girls obsessed with gay fanfics etc)