Dangerous Curves Ahead (Suncoast Society 38, MMM, BDSM) by Tymber Dalton. (Note: This is the third book in what's informally called the South Dakota Trilogy sub-set of the Suncoast Society series. Those three books are Beware Falling Ice, Beware Falling Rocks, and Dangerous Curves Ahead.)
Dr. Justin Rede has just graduated college…and just come out of the closet. During a trip to Florida to visit his sister, Rachel, and her fiancé, Andrew, they introduce Justin to their kinky friends in hopes they can help talk Justin into moving from South Dakota to sunny Sarasota.
Including hunky older, experienced Doms, Wade and Glen.
Wade and Glen are newly married since the marriage ban fell, but have been together for years. Sure they’ve played with thirds before, in the dungeon as well as in their bed. But their standing rule has always been it’s just for fun, not for love.
Until they meet Justin.
Now the two sadistic Doms realize something’s happened they never expected—they’ve lost their hearts to Justin. But can they convince him they’ve changed their minds and want him for life before someone else comes in and scoops their perfect subby unicorn right out from under them?