So That's the Deal: Will Being Physical Lead To Love?

This review contains spoilers. It's the "friend of big brother"-trope, with everything that comes with it: the overly protective big brother, some kind of sibling thing and having a secret relationship because of that.
I think the relationships aren't portrayed well though. For instance: for the siblings, you should have started with the fact that the big brother basically raised her so that I as a reader would understand their relationship from the start, instead of that fact being thrown in in a conversation 9 chapters in to explain his behaviour looking back.
The main characters also cannot explain what and why they are in love with each other.
But, you know, it has the dirt one expects.