'The Vow' Director on Casting Rachel McAdams and Channing Tatum (Video)

"I just thought that it was really important to find an actress who you are rooting for even if she was being cold," Michael Sucsy told THR about casting McAdams for the lead.

The Vow is a romantic drama about a couple whose world is turned upside down after Paige (Rachel McAdams) loses her memory in a car accident and has no recollection of her husband, Leo (Channing Tatum), or the past five years of her life.

Director Michael Sucsy (Grey Gardens) may have been making a movie focusing on the loss of memory, but he told THR he needed his lead actors to be memorable and likable.

PHOTOS: Rachel McAdams and Channing Tatum Shine at 'The Vow' Premiere

“Rachel was the very first actress that we ever spoke about in any meeting that I ever met on for this film,” he told THR on the carpet at the premiere event. “And I just thought that it was really important to find an actress who you are rooting for even if she was being cold.”

Sucsy added that McAdams, who has starred in several other romantic dramas including The Time Traveler’s Wife and The Notebook, brought the right likability to the part.

VIDEO: 'The Vow' Stars Channing Tatum and Rachel McAdams Talk Chemistry, Romance

“The character of Paige when she dissociates from Leo, you want to keep rooting for here even if she’s not feeling the love for him, you want to still feel the love for her,” the Emmy-winning director added.

As for Tatum, Sucsy said he had his doubts about the actor, who’s starred in Public Enemies, G.I. Joe: The Rise of Cobra and Dear John.

VIDEO: 'The Vow' Trailer With Rachel McAdams, Channing Tatum

“I thought, ‘Well, I don’t know. He’s kind of played military characters, kind of cold, I don’t know, this guy’s really warm,’” he said.

But his doubts were erased after he flew to New York and met the 31-year-old actor. “This guy’s got a huge heart. He is a white knight. It’s who he really is,” said Sucsy. “I don’t think anyone’s really seen him like that. Even in Dear John he still played military even though it was a romantic story. And I just thought, he’s perfect for Leo.”

One of the most challenging aspects of making the Screen Gems romantic drama, which is inspired by a true story, was keeping McAdams’ character likable when she often acts out while struggling to remember the last five years of her life.

“We had to sort of measure or regulate the ‘bitch factor’ for Rachel’s character,” said Sucsy. “I wanted to have the most amount of flexibility in editing to really regulate that character.”

While the audience will probably enjoy it, Sucsy also added that some of the nude scenes were also a little tougher to shoot.

“I think whenever you have actors on set who are wearing no clothes it’s always awkward,” he said. “You’re not really sure where to look and what to say and what to do.”

In one scene, Channing’s character walks in on Rachel’s character Paige while she’s changing, but for Paige, Leo is a stranger she doesn’t know at that point.

“I don’t understand why Americas are so weird about nudity, but we are,” said Sucsy.

The Vow opens in theaters on Friday, February 10.