YES you put it perfectly into words. Without Joseph the story would flow fine, maybe a few tweaks here or there but still fine. Without Erez, however, there wouldn't be a story to begin with. Plus Erez and Keira have a great dynamic, and I feel their relationship is progressing more naturally. Joseph doesn't have many personality traits besides 'nice' and 'crush on keira.' Him and Keira's relationship feels kinda forced(?) to me, like they have sweet moments and all but it feels artificial