Always You - The DeLaurentis Brothers, #1

Izzy might not be long-limbed, curvy, sophisticated, or blonde - all the attributes Alessandro DeLaurentis seems to require in a lover, but she loves her sister more than anyone else in this world. If saving her sister's life means propositioning the elusive millionaire, Izzy will do it - even if he laughs in her face. But now that he's agreed to help her, she has an even bigger problem. If she can't reign in her feelings for Alessandro, she risks losing more than her heart.
She could ruin everything and lose her sister too. The only people Alessandro cares about are his two younger brothers. He has no interest in love but when Isabella Sullivan offers to play the part of his girlfriend in a ruse that will strike a blow at the man who destroyed his family.he doesn't hesitate. But having the sweet and innocent Isabella in his life throws his carefully organised world into chaos.
This is the first book in The DeLaurentis Brothers series but can be read as a standalone novel.