Found Hearts. Hibiscus Hearts series, #6

Lena Luton always had dreams of leaving Maui for the mainland, but with a chaotic upbringing like hers, it felt impossible. Working hard to get into college, and with her sister footing the bill, she knew she had to make it. But her daddy issues run deep, and after a disastrous year, she ends up back home and hiding from her sister. Eli Hamilton has landed his dream job as a firefighter on Maui, but his playboy past returns to put him in his place.
Single fatherhood was never in his plans, yet that's where he finds himself, and now he's in desperate need of help. Lena and Eli's worlds collide when she takes a job as his live-in nanny. And as they grow as a family, they find themselves falling for each other. But Lena's past is closer than she thinks, and what she's kept hidden could ruin the heart she's finally found.