Her Cowboy Billionaire Best Man by Liz Isaacson

Celia is finally ready to date again—but not the man whose family has a century-old feud with hers…
Celia Armstrong has spent almost two decades mourning the loss of her husband, raising her two girls, and taking care of everyone except for herself. When her best friend gets married, Celia’s right there, taking care of everything at Whiskey Mountain Lodge.
Before the ceremony, she catches sight of a handsome man in a cowboy hat she hasn’t seen before. When she finally gets a good look at the man when she gets paired with him in the wedding party, she realizes he’s Zach Zuckerman, from the family across the street that has a decades-old grudge against her family.
Zach doesn’t want to be at the wedding, just like he doesn’t want to get involved with Celia. But the attraction between them is intense, and they start dating. His brothers will be livid when they find out who his new girlfriend is, and he and Celia start to investigate the root of the animosity between their two families.
Amidst her daughter’s wedding and dealing with graduations and family events, Celia and Zach learn that her family is the reason the Zuckermans have hated the Abbotts for so long. Zach tries to talk to his brothers and father, but his pleas fall on deaf ears.
Can Celia and Zach overcome family objections to build a future together? Or will their relationship be a casualty of the generational war?