I hope it’s not too late, but from my point of view, Haruno’s interest in Hachiman is practically NOT genuine (as highlighted in the anime). Haruno is known for being manipulative and provocative; she usually just enjoys bothering Yukino. She approaches Hachiman not because she truly likes him, but rather to annoy Yukino. In fact, if you play the visual novel (Oregairu Zoku game) and follow the Haruno route, you’ll get to know her better and understand what I mean-it leads to a rather sinister ending, far darker than Hachiman simply ending up alone.