With You All the Way by Cynthia Hand

Ada’s life is a mess. She just caught her boyfriend cheating on her after a humiliating attempt at losing her virginity, and she’s had it up to here with her gorgeous older sister’s unsolicited advice.

But things really hit the fan during a family vacation in Hawaii, where Ada discovers her own mother is having an affair. Apparently, everyone is falling into bed with people they shouldn’t. Everyone except Ada. But when Ada decides she’s going to stop trying and start doing—sex, that is—her best laid plan overlooks an inconvenient truth:

Feelings, romantic or not, always get in the way.