The siblings should just date both of them.
But she's hot (you're completely right though).Honestly really am losing interest in this. The older sister just turns me off completely. I really despise untouchable "cool" older sister characters where the brother is subservient. Both protag have limited agency because of her presence with the boy even less so compared to the girl.
Don't even get me started on her lesbian fangirl. Probs 2nd worst character.