One sided? You mean, did Sholto love John and John didn’t love Sholto? Obviously John loved Sholto. Why would Sherlock be jealous if it wasn’t obvious that he did? Sholto is clearly John’s ex, even if they didn’t actually shag.
I can’t tell if they shagged or not. I could go either way on that. No pun intended.
I do not think John considers himself bisexual, if only because of the way he reacts to people thinking Sherlock’s his boyfriend. I think if he were secure in his bisexual identity he’d be unlikely to counter suggestions that he and Sherlock are a couple with “I’m not gay.” That doesn’t make sense. (“But he’s not gay,” you say to me. “He’s bisexual!” Okay, but if you’re bisexual and someone asks you if your friend is your partner, you don’t say “I’m not gay!” You’d say, “Nope, just friends!” Which is what most people should fucking say unless they’re helplessly clinging on to the last vestiges of their heterosexuality, just sayin’.)
Sholto is obviously a parallel for Sherlock. John has intense emotional relationships with men that may or may not become sexual. It hasn’t with Sherlock, and maybe it never did with Sholto either. Maybe it could have in both cases.
JOHN HAS SO MUCH LOVE TO GIVE. It can’t be restricted to just one gender. FREE JOHN WATSON! FREE JOHN WATSON’S REPRESSED LIBIDO!