>>279579990
In a very subtle and underepresented way, Louise and Saito do progress at a glacial pace:
Season 1: Saito is starved and sleeps on the floor
Season 2: They sleep together and are adventuring teammates
Season 3: Saito's harem expands but it's shown he gravitates towards Louise one way or the other
Season 4: Saito is ready to breed and louise gets more vulnerable, when the adventure wraps up It's over

The thing is at least Zero no Tsukaima has a million things going on. Just by looking at Kirche on ep1 you imagine it's a Harry Potter porn parody, and it is. It's a sexual comedy first as well as an action adventure, fantasy school isekai harem ecchi romance with pseudo historical elements. And if you allocated more screentime and thought to the main romance you betray the elements and girls that, as this thread proves, the audience also loves.