Big Summer by Jennifer Weiner

Six years after the fight that ended their friendship, Daphne Berg is shocked when Drue Cavanaugh walks back into her life, looking as lovely and successful as ever, with a massive favor to ask. Daphne hasn’t spoken one word to Drue in all this time – she doesn’t even hate-follow her ex-best friend on social media – so when Drue asks if she will be her maid-of-honor at the society wedding of the summer, Daphne is rightfully speechless. Drue was always the one who had everything – except the ability to hold onto friends. Meanwhile, Daphne’s no longer the same self-effacing sidekick she was back in high school. She’s built a life that she loves, including a growing career as a plus-size Instagram influencer. Letting glamorous, seductive Drue back into her life is risky, but it comes with an invitation to spend a weekend in a waterfront Cape Cod mansion. When Drue begs and pleads and dangles the prospect of cute single guys, Daphne finds herself powerless as ever to resist her friend’s siren song”–Amazon.com