SciFi and Fantasy Book Club discussion

Hello everyone! I am looking for a book where the protagonists(s) have to unite two worlds/countries preferably with a female protagonists and with romance in it (enemies to lovers).
I am grateful for any suggestions :).
(I hope the questions makes sense and is in the right place)

Poison Study fits this criteria

Maybe a stretch but how about The Left Hand of Darkness by Ursula K. Le Guin.

I'll be following this thread; if I manage to think of anything I'll post.

The Sarah Maas books
This Is How You Lose the Time War
Strange the Dreamer
An Ember in the Ashes I think should fit the bill
Elantris or Warbreaker
Daughter of the Forest
The Blue Sword