Mark Duplass and Charlie McDowell protect 'The One I Love'

Mark Duplass and Charlie McDowell of 'The One I Love'

Mark Duplass and Charlie McDowell at the James Hotel ( 55 East Ontario ) on August 20, 2014. ( Sean Ely / RedEye ) (Sean Ely/RedEye / August 20, 2014)

Mark Duplass discovered how damaging spoilers can be when he went to see “The Crying Game” at age 14.

“It took me like two weeks to get to the theater, so I had held off [knowing] everything,” says the 37-year-old star of “The One I Love” at the James Hotel. “Literally right as the lights went down, the woman in front of me leaned over to her husband and was just like—and I’m not going to say it here for people who haven’t seen it—but was like, ‘Don’t worry, when this happens, it’s not that graphic.’ And I was like, ‘Un[bleep]ingbelievable! I’ve been trying to hold this for two weeks!’”

“The One I Love,” opening Friday, doesn’t have a twist of “Crying Game” proportions. But Duplass (who’s married to his “The League” costar Katie Aselton) and 31-year-old, first-time feature director Charlie McDowell (son of Malcolm McDowell) are smart to want viewers to experience the unusual, insightful romantic drama without knowing too much beforehand. The basics: Ethan (Duplass) and Sophie (Elisabeth Moss) go to a retreat recommended by their therapist (Ted Danson, McDowell’s stepdad) to repair their marriage and discover something very unexpected.

By the way, Duplass (recently in “Tammy” and “The Mindy Project”) didn’t speak up to the woman who ruined “The Crying Game”: “I was 14. I was scared of adults.”

“The One I Love” addresses the issue of allegedly presenting the best version of yourself at the beginning of a relationship. To what extent can first dates be seen as a degree of false advertising?

Mark Duplass: In my experience they are usually that way. To a large degree.

Charlie McDowell: They’re only that way.

MD: There are occasionally these couples that you meet that they’re like, “Oh, we were friends for like five years, and then we got together.” And I’m like, “I think that might be the way to do it.” You kind of sneak in there without any of the faking going on. When I met my wife Katie, it was through friends of friends and it was on New Year’s Eve, and I had just kind of had a mutual breakup with this girl a couple of months before, and [Katie] was asking me about it. And I remember in my head as I was telling it to her, I was like, “Why am I lying about this? Why am I lying about this?” But I was doing it!

And I told her this story about, “Look, I just knew I wasn’t ever going to be truly attracted to her in the way that it needed to happen, so I just looked her in the eye. I just told her exactly what I felt. I was really honest with her about it.” It was not at all that way! I lied. I was backhanded about it. But she thought it was the coolest thing, and I remember her telling me that like a year later, “I just loved that story.” And I was like, “It kinda didn’t happen that way.”

How would it work out if people were super upfront, even on the first date?

MD: Are we talking bathroom-with-the-door-open kind of thing?

Maybe not that upfront.

CMcD: I can’t tell if more people would be together or less people would be together. It’s something we’re all conditioned to do is look at someone—I think you do it with friends, you do it with how you communicate with people, you sort of adapt.

MD: You do it at parties.

CMcD: Yeah, you adapt to who they are. If someone’s really shy, then for me I like become the guy who’s super-chatty and talky. And if someone’s super-chatty and talky, I literally shut down. I think it’s a lot of adapting to what you’re getting from other people.

Can you put these elements in order in terms of what you think is most important in a relationship: trust, communication and having fun together?

MD: I wouldn’t use those three in particular. For me it’s a very subjective thing. The most important thing for me at this stage is people who are emotionally aware and that they know when they’re being insecure, they know when they’re being an asshole, they know when they’re being certain ways so that you can have good conversations about that. I personally don’t believe that you can be in a long-term relationship with someone who doesn’t know themselves and have the ability to laugh at themselves. It’s a killer in my opinion.

CMcD: Yeah, I definitely agree with that.

MD: Great butt, also.

CMcD: Yeah. Something that you said is for me communication is a huge one. Especially being in this business, there’s constantly traveling and moving around, and the idea is it’s hard to be on the same page when you’re not in the same place. The biggest one in my relationship is just communication.