The Wayward Dukes' Alliance.
A wayward duke is "difficult to control or predict". The "hero" is either be a duke or expected to inherit a dukedom. None of these dukes want to be trapped by marriage and form a pact to help each avoid matrimony by any means necessary.

This Christmas the Wayward Dukes' resolve is tested. Can their alliance hold true, or will the magic of the holiday be too much for even them to resist. One by one they will fall. It's only a matter of how hard and fast they will succumb to the one woman they're destined to love. All their ladies want for Christmas is their own wayward duke, and they are each determined to have their wish fulfilled.

Seven Christmas stories in the Wayward Dukes' Alliance in one book.

Her Duke to Savor by Dawn Brower
Unwrapping the Duke by Jane Charles
Never Beg a Duke by Alyssa Drake
Wish Upon a Christmas Duke by Amanda Mariel
A Duke for December by Nadine Millard
What the Duke Desires by Ari Thatcher
Boxing with My Duke by Anna St. Claire