IIN that a fuckbuddy is falling for me?

I suppose it depends how strong her feelings are. If they're just there a little bit then I would keep it going, but if not then I would let her know and break it off.

Also, if she's a feminist, be careful how you tell her you don't have the same feelings, I wouldn't be surprised if she tries to slap you with a rape charge if she knows your love is unrequited.