I really like how this is one of those otaku x popular girl couple wish fulfilment stories, but it is really properly motivated why the girl likes him.
Too often she just kinda does, either for no reason or something really spurious, like him saving her from something and she's so grateful she just donates her entire life to him, or they're like secret childhood friends who haven't seen each other for 10 years, and that 5-year old affection is so strong she donates her entire life to him. And too often that means he can continue being his antisocial greasy annoying self and just receive constant unconditional love in return.
But here, not only have they been best friends for years and years, properly grounding their close relationship, but that doesn't even mean she likes him romantically at the start. Very specific circumstances, among other things involving him making active effort to improve his physical appearance and social skills, are required for her affection to turn romantic.
It's so much easier to root for the male protagonist when it feels like he's actually earning his progress.