Books like The Opposite of Here

There's no hiding on a cruise ship - not even from yourself. Natalie's parents are taking her and her three best friends on a cruise for her seventeenth birthday. A sail-a-bration, they call it. But it's only been a few short months since Natalie's boyfriend died in a tragic accident, and she wants to be anywhere but here. Then she meets a guy on the first night and sparks fly. After a moonlit conversation on a secluded deck of the ship, Natalie pops down to her cabin to get her swimsuit so they can go for a dip. But when she returns, he's gone. Something he said makes her think he might have . . . jumped? No, he couldn't have. But why do her friends think she's crazy for wanting to make sure he's okay? Also, why do they seem to be hiding something from her? And how can she find him when she doesn't even know his name? Most importantly, why is the captain on the intercom announcing the urgent need for a headcount?