@kantha,
@RangTime
I think Tadano's also very conscious of all the
other ways you can like someone. He knows he's popular now, if popularity is suitably defined. Classmates find him friendly and approachable. The girls in the class like to tease him and practice romantic moves like hand-feeding on him. His Tadano-chan persona attracts the boys and can befriend the most socially awkward girls in a matter of minutes. Najimi flirts with him constantly. And Komi, of course, is desperately lonely and has prized Tadano as her social lifeline since her first contact with him.
But in most of those cases, that doesn't mean those people feel specifically romantic love for him; their feelings are somewhat different shades. So he's cautious of assuming Komi and Manbagi's current emotions are truly romantic either, especially since they're both kind of psychologically fragile, and easy to hurt or manipulate. (Tadano is aware of how good he is at manipulation, but he's not particularly proud of it.)
So yeah, I don't think Tadano's dense at all. He's just a couple of years ahead of the rest of the school in emotional maturity, and knows love is more complicated than the standard manga teenager's inarticulate blushing desire.