Workout Partner Woes

So I’m this personal trainer, right? And I’ve got this client named Lily, she’s in her twenties and really into all the fitness stuff. We click pretty well, she works hard and laughs at my dumb jokes. Thing is, lately we’ve been bumping up against that line between coach and just... friend with benefits. Like, I caught myself one day thinking about what it would be like to mix our sessions up a bit, y’know? But I’m engaged! And I shouldn’t even be flirting with the idea of crossing over into something more than professional. But there she is, all sweaty and stretching out on the mat in front of me... It’s hard not to think about it sometimes, you know what I mean? Like, it was funny at first but now every time we work together, there's this tension that isn’t really supposed to be there. Maybe I need a new client or something.