Once and For All by Sarah Dessen
Louna is a high school senior set to graduate in a few weeks. Her summer job is (as always) helping with her mom's wedding planning business. Her college plans are set, her best friend is in place, and there is no romance for Louna on the horizon--which is just as well. She has survived being in love with the perfect boy, but recovering from that wasn't easy and she's not eager to do it again.
Then Louna meets Ambrose: trouble-making brother of the bride, always late, always fidgeting, always irreverent, always flirting with every girl he meets. Louna wants nothing to do with Ambrose.
Because this is a Sarah Dessen novel, readers totally know where the story is going and where all the characters will end up. The journey is familiar and relatively predictable, but it's still kinda fun. Behind-the-scenes details of wedding planning are amusing, the banter between characters is catchy and cute. There are some poignant details scattered gently into the story, but this is essentially a rom-com that should have starred Meg Ryan and Tom Hanks when they were both 17 years old.
Gold star for the appropriate mention of a condom, but no body parts on the page.