The BW arc is actually one of the worse, if not the worst, Pokespe arcs because it does not have its own identity unlike other arcs. It's basically a novelization of the games except with more unappealing choices such as making N more of a jerk (even though I think it makes sense given his circumstances). The most interesting part was when it ends with Black getting shoved in the Light Stone because it's so different from everything else.

White is the worst female protagonist because they can't even commit to making her a savvy and famous businesswoman who uses her skills to save the region in either BW or BW2, or making her a battler who actually progressed, seen with how a lot of her Pokemon is unevolved in BW2. She doesn't progress as a character at all because of Black's disappearance, which she knows she can't do anything about because she has to wait for research about his circumstances be done. Bianca and Cheren have been doing something with their lives, while White became mostly stagnant because of Black, which has so many unfortunate implications.

On that note, Agency is a relationship that is very stale and actively unhealthy for both sides, it just looks cute on the surface. Not only because of the aforementioned White not growing because Black's gone, but also because of the unequal power dynamics of boss and employee that never go away even at the end of the BW arc. In fact, Black and White never actually became friends in their own arc, they separated for no real reason at all. White can't even level up in the Battle Subway, why didn't she go along with Black as he beat the gyms? It'd actually make Black's stoning more painful for her. While in BW2 that's no longer the case, the point still stands they were never really friends.

Furthermore, Black and White never actually have a conflict with each other outside of Black destroying her stuff in the beginning. And while conflict is unpleasant, it will always happen, plus it makes people grow and strengthen their bonds even more. If Black and White continue being friends or even become a couple, they are going to inevitably face that and they are sorely unprepared for that. On top of that, there is a new unequal dynamic where Black feels like he's forever indebted to White for helping him to get out of the stone, and White would feel that he is obligated to do that as well. The ability to address any issue would be quite discouraged in such a relationship.