TORONTO -- Passionately kissing a woman in front of her husband is typically not advisable, but in Anthony Mackie's case, he was urged to do so.

Mackie stars in "Shelter" alongside Jennifer Connelly, whose husband, Paul Bettany, directed the film.

The movie, which tells the stories of two homeless people struggling their way through life on the streets of New York, is punctuated with a few scenes of tender romance, which initially presented a bit of a stumbling block for Mackie.

"It was difficult at first," he said with a bashful smile during an interview at the Toronto International Film Festival. "But Paul really put me at ease."

Mackie, who plays Tahir, a seemingly gentle man with a dark past, said he had to work his way through his shyness around Connelly during the most intimate moments between their two characters.

"It was funny because I would always say, 'well, maybe I shouldn't, maybe I shouldn't,' and Paul was like, 'no, go for it,"" Mackie said. "He encouraged me day in and day out."

The actor, who has appeared in "The Hurt Locker" and "Pain and Gain" among other titles, said he eventually realized that Bettany was focused on his job.

"We were all professionals, we were all there to do a specific job, and you know, it was childish of me to think that Paul would perceive or take my work with his wife in a certain way other than what it was," he explained. "So once I let that go, it was a good time."

Connelly, meanwhile, appeared to have no qualms whatsoever, Mackie said.

"Jennifer was great," he said. "Jennifer was a lot of fun, easy to work with and just really made the movie enjoyable."

The Oscar-winning actress embraced her role as Hannah, a woman who is slave to a devastating drug addiction, said Mackie.

"She really allowed herself to go to a place that, being so beautiful, a lot of people would never expect her to go to," he said. "She took that on whole heartedly and really just got ugly for the role. She got really messy, that's what kind of gave me the courage to go further with my role."

"Shelter" is Bettany's directorial debut. The films opens at the Toronto International Film Festival on Friday.