The Wingman by A. Poland

Nathan, a college student with a thing for funky hats and a definite not-thing for the great outdoors, has been a wingman extraordinaire for his lifelong best friend Lorcan for as long as either can remember. With his innate ability to talk endlessly about how great Lorcan is to anyone who’ll listen, Nathan has always been the best man for the job—even if he’s secretly waiting for the day when Lorcan will realize that Nathan is the only guy for him.

But then, Lorcan sets his sights on Miles, the suave, leather-jacket-wearing musician with a love of mountaineering and a family of six overprotective sisters, and Nathan must once again put his wingman skills to work.

Trouble is, Nathan is getting tired of the old routine, and Miles is the only human being on the planet immune to Lorcan’s charm. Not to mention that Miles’s interest is immediately piqued by the outspoken and completely oblivious wingman.