I've said it a few time but a really fascinating part of the whole Heated Rivalry phenomenon for me has been watching all these people crashing into the genre without seeming to be aware there's even a genre at play.
Heated Rivalry (book and presumably show) is a Romance. Not a story with romantic elements, or a story with romantic themes, not a love story. It is a romance story in the genre of romance, the same way you think about sci-fi or fantasy as a genre.
To be a romance means that it has 1) a central love story that is the focus; and 2) a Happily Ever After ending, or at least a Happily For Now.
It's been really fascinating to watch people comment/complain/observe that the show feels like a romance because...yes. Exactly. And it's been disappointing (but not at all surprising) to see people say the story would be better and more legitimate and more worthwhile if it just...maybe could be a different genre altogether.
It's been equally interesting to watch people not seem to fully realize that Shane and Ilya's story is a romance. Because the thing about romance is you know roughly the ending (happily ever after), so the real story is in the how. And in my opinion that's part of what made HR so popular--it's engaging with and inverting a number of popular tropes/genre formulas/reader expectations in the way that 'how' comes about. It's been really interesting seeing people engaging who aren't necessarily aware that these conventions even exist, let alone realize they're being played with.
I've also been really struck by the very frequently repeated opinion that the show and/or book feels like fanfic (which not always but sometimes seems to be an insult). Because going back to that definition of a romance (a central love story and a happy ending)...guys its not that this romance feels like a fanfic. Its that fanfic is very frequently a romance.
The vast vast majority of shipping fic especially is focusing on 1) the central love story and how the relationship works, and provides 2) a happy ending/happily for now. So YES this romance reminds people of their favorite fics. Those fics are influenced by, informed by, and created from the culture backdrop of romance conventions, tropes, structures, and formats. It's a recognition of genre, and again, absolutely fascinating to watch people drawing that connection without seeming to be aware of the genre itself.