"Plus he's harboured this secret love for an unimaginably long time -- it must be so hard to suddenly have it in public view and treated almost jokingly (though ZYL is very sincere underneath)."

Oh, this is SUCH a good reason, I'm totally grabbing it as one of the explanations, yes! I think he at least knows at this point how sincere ZYL is, but everyone else is straight-up joking and dismissive and has absolutely no idea how important all of this is, and I can totally see how it can be distressing!