Rick does this one thing a lot: develops romance as opposed to developing characters. romantic love = finding maturity. When a character can’t or won’t find romantic love, the arc is closed for them in this aspect (hence Thalia). One of the few cases in which hasn’t happened is with Frank who, in hindsight, lost weight as a symbol of growing (shitty thing to do). To be fair, Piper and Jason both progressed AFTER being together but a lot of their progress had to do with overcoming jealousy and insecurity in their relationship (same happened to frank in MoA as well, but it’s ok cause with all the bullying in that book i forgive him for anything). It’s not like all characters went through this, but look at Percy and Annabeth and try to think of them from the first to the second series and how it went from being friends and fighting together to just Rick saying they’re great friends all the time instead of actually showing anything other than their NEED TO BE WITH EACH OTHER OMG THEY LOVE EACH OTHER SO MUCH. The characters kind get stuck there.
Or else it happens what happened to Jason, Piper and Nico which that their progress WAS their love life.
That said, Reyna, luckily, got her character development. without turning into an amazon or a hunter or the oracle which is how he solves these things (but he did give her an open ending that sounds suspiciously like someone is gonna make cameos in a future series whatever). That said, because Reyna progressed so much while Leo stood the same place or even got worse, I could not see these two, as of HoH together. Not because of Caleo, because, at the end of HoH there’s still room for both Reyna and Leo to learn and grow together but as of BoO, Reyna is such, such a different person than she was at first, that she would never find support in a person like Leo.
A lot of people who are anti-leyna thought of that before, but as I saw it (and still see it) the Leo and Reyna of the first few books, had many traits in common and opposite thoughts that could clash in productive ways. The Leo of Caleo and the Reyna who understands where she belongs and is fulfilled by it, could never properly help each other as deeply.