It’s not just about the boys in blue, says “End of Watch” female leads Anna Kendrick and Natalie Martinez.

The cop flick, which stars Jake Gyllenhaal and Michael Pena, provides a snapshot into the lives of two L.A.P.D. officers.

“I don’t think I could do it. I have so much respect for people…who can give their hearts to cops and start families with people who put their lives on the line,” says Kendrick on playing a character who’s involved with a police officer. “I don’t pretend to be somebody who’s strong enough to do something like that.”

Kendrick signed on for the role after reading the script written by director David Ayer (“Training Day,” “The Fast and the Furious”) and understanding the emotional tapestry he created between the characters.

“If you had described it to me, it was just a wife/girlfriend role and it wouldn’t be that interesting,” Kendrick says. “But when I read it, even though (my character) Janet wasn’t in it a lot, she was incredibly important in rounding out the world, and obviously the same goes for Gabby (Martinez’ character) . Even the way the guys talk about the women when they’re not on screen, it feels as though they are present throughout.”

The film boasts an ensemble cast, including Cody Horn, America Ferrera and Frank Grillo; but the majority of screen time is devoted to Gyllenhaal and Pena, focusing on how the people in their lives affect them when they’re on the job.

While Kendrick plays a new addition to Gyllenhaal’s life, Martinez plays a seasoned cop wife.

“I know these women and they’re very, very, very strong,” Martinez says about her role. “You have to be when these men come to you and have these hard days. You’ve got to be that rock for them. And I think with this film, the most important thing was showing you the relationship between a couple, instead of the qualities that I have.

“In the little time you do see us, we show you that we’re that couple that is strong, and nothing is going to break us and we’re there for each other. And that alone is a sacrifice.”

In between the dark and gritty themes of the film, Kendrick does admit there were some lighter moments on set. In particular, she describes a moment where she gets to let loose and bust a move with Gyllenhaal during a wedding scene.

“We were both like, ‘wait, what are you talking about?’” remembers Kendrick when they found out they would be dancing on screen. “Because that was not in the script!”

“It said that they do a cheesy, choreographed dance (and) in a movie like this…there are so many things where you think, ‘well I think this is the day I really have to trust my director.’ But doing the wedding dance was the day we really had to just trust our director because we were like, ‘are you sure about this?’”

The turnaround time to learn the dance was really quick, according to Kendrick. That’s why she made sure she knew the moves in and out first, as Jake relied on her to guide him.

“I think Jake and I had a couple of rehearsals at lunch time,” she says. “We learned it as fast as we could. Jake was not great at learning it, so sometimes he was watching me a little bit, in the movie.”

Despite their limited screen time, the girls made sure their characters were fully fleshed out when audiences meet them for the first time. And for Kendrick, that meant rehearsing scenes that were never intended to be included in the film at all.

“My rehearsal period was just with Jake, and we didn’t rehearse anything we shot or intended to shoot,” says Kendrick. “We rehearsed a scene that David wrote that predates when we first meet Janet. We rehearsed that scene so many times and it really laid out that foundation for how I felt about him, how he felt about me.”

She also added, “I wish I could do every movie like that  - have somebody write me a couple of scenes before you meet me, or any of the characters, to feel like this is where I’m coming from.”