Shifting Hearts — Silvia Violet

Book 6 of the Wild R Farm series 

After experiencing what happens when someone you love walks away and never looks back, Brandon decided love was for fools. Then he spent a summer with Zach. He struggled against feelings that grew every time he and Zach were together, telling himself they were just having a fling. When Zach confessed his love one hot summer night, Brandon panicked. He scoffed at Zach and made sure he walked away first. 

Three years later, their paths cross again when Zach becomes the vet at Wild R Farm where Brandon works. Brandon realizes his feelings haven't changed, but Zach treats Brandon with scorn despite Brandon's every attempt to show Zach he's no longer the self-centered man he used to be. When a night out ends with Brandon driving Zach home, confessions are made on both sides, and hope begins to build in Brandon's heart. 

Look for the rest of the Wild R Farm series! 
Finding Release (Book 1) 
Arresting Love (Book 2) 
Embracing Need (Book 3) 
Taming Tristan (Book 4: a short story) 
Willing Hands (Book 5) 
Wild R Christmas (Book 7)