They're not really giving step-siblings, it seems more like a childhood friends-to-lovers ...

They're not really giving step-siblings, it seems more like a childhood friends-to-lovers trope. Like they were aware they weren't siblings and it was a favor between the parents, for her to stay with them. He was even annoyed she was using his family's money. It's similar to stories where they live near each other/ are neighbors, & they are constantly together because of their parents' friendship.

It's kinda cute if no one will sleep with a third party.