The Substitute by Sean Ashcroft

Flynn hadn’t expected to be getting married anytime soon, definitely not this weekend, and definitely not to a man.

When his flakey younger brother walks out on his fiance on the eve of their wedding–and therefore robs the poor guy of his chance to go back to school–Flynn steps in to clean up the mess Aiden’s left behind, like he always does. Getting married wasn’t exactly on his to-do list, but what happens in Vegas stays in Vegas, right?
Except now he’s invested, and Zach’s a sweetheart who doesn’t take him for granted, and after a spur-of-the-moment kiss, Flynn’s forced to confront some feelings he’s never acknowledged before. Feelings for another man.

But with Zach protecting his broken heart and Flynn afraid that he’s just a substitute for Aiden looming over them, can they be happy together? Or will they let their doubts and fears tear them apart?