I've got a list of books that don't contain annoying romantic sideplots! Sometimes romance is mentioned, or side characters are involved in things, but the main character isn't allosexualy exploding all over everything like in most books. 😂 It's compiled from personal experience(occasionally I completely mentally melt down and demand suggestions for books that contain no romance from my friends/colleagues), and this is what I've got from my reading tracker and TBR(starred books are ones that were suggested but I haven't read, so I can't vouch for them personally):

Elatsoe, by Darcy Little Badger
Comfort Me With Apples, by Catherynne Valente
The Girl from the Well, by Rin Chupeco
Remote Control, by Nnedi Okorafor
From Below, by Darcy Coates
The Many Deaths of Laila Starr, by Ram V
And Then I Woke Up, by Malcolm Devlin
What Moves the Dead, by T. Kingfisher
Nuclear Family, by Joseph Han (I recall sex/romance is mentioned with regard to PoV characters, but they're not interested)
Gideon the Ninth, by Tasmin Muir*
Madam, by Phoebe Wynne*

My apologies if I've somehow forgotten a romantic subplot in one of these. To the best of my recollection, they're safe! Also, the fact that my tracker contains 68 books(not to mention the TBR list, which is unnumbered) and I still only have 11 items on this list, despite actively seeking out this type of material, just goes to show how uncommon these books actually are.

EDIT: Just finished Rust in the Root by Justina Ireland, and I can also add that to this list! The main character has a very slight crush on a secondary character, but it doesn't amount to anything and barely even exists.