You might think Josh Radnor’s commitment to the hit CBS sitcom How I Met Your Mother – in which he’s the “I,” always on the lookout for “Your Mother” – would make a side project as ambitious as Happythankyoumoreplease all but inconceivable.

Yet according to Radnor, Happy, the indie romance he wrote and directed, which opens Friday after winning standing O’s at this year’s Sundance Film Festival, would never have been possible without his high-profile day job. If anything, the success of Mother has allowed him to broaden his artistic horizons.

Not that Radnor, 36, planned to direct – initially, he just wanted to create a memorable character. In Happy he does that, playing Sam Wexler, a restless author struggling to make the transition from short stories to novels.

It’s a metaphor on more than one level – Sam is equally inept in matters of the heart, as he tries to turn a one-night fling into something more substantial – but Radnor also sees his character’s arc as a reflection of his own venture into untested waters.

He didn’t at first. “Someone mentioned that, and I found it fascinating that I’d never made that connection,” he says. “But the interesting thing about writing is that eventually the characters start talking to you.

“You demand something of them, and they refuse to do it because it doesn’t feel right. They tell you where to go. I had strong ideas, but I didn’t know quite where I was headed, and sometimes where I ended up surprised me. I never realized the movie would become so much about gratitude, for instance, but that’s just one aspect of my own life that got stirred into the pot.”

Although Radnor stars in Happy, the story is an ensemble piece, about a group of young New Yorkers (Malin Akerman, Kate Mara and The Wire's Pablo Schreiber, among others) stumbling their way through ill-fated romances, near breakups and, in Sam’s case, an unlikely attempt to adopt.

All their stories deal, in one way or another, with the difficulty of making honest emotional connections, and the joy those connections can bring. It’s a subject Radnor treats without a hint of condescension or cynicism.

“I used to be very attracted to irony in the movies, but as I grow older I’m much more attracted to sincerity,” he says. “I want to find the authenticity in people. Besides, when someone’s always saying the opposite of what they really feel, it gets tiresome. It requires too much guesswork. You can’t trust those people, and I wanted people to trust this movie.”

Happythankyoumoreplease is now playing at the Landmark Embarcadero Cinema. For tickets, click here.