A Battle to Save a Marriage

For Kathryn and Heath, a couple married for 12 years, what once seemed like an unbreakable bond now teeters on the brink of dissolution. They have found themselves at a crossroads in their marriage that very well could lead to a divorce.

The pair have an 11-year-old son along with the two teenage daughters Kathryn has from a previous marriage.

Blending the family always has been a point of conflict for the pair, but Heath's extramarital affair, which he said is long over, and financial stresses have strained an already fragile union.

VIDEO: Trying to Save a MarriagePlay

Three weeks ago Heath moved out and now the two hope family therapist Terry Real can help them save their marriage. "Good Morning America" followed them through the counselling sessions.

Though the couple didn't ask for their last names to be withheld, ABC News has not released them in order to protect the pair's privacy.

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Battling Affairs, Difficult Familial Relationships

"I'm fearful of a lot of things that have happened in our relationship in the past," Kathryn said during a counseling session. "When Heath isn't happy, he'll look to other women."

"What I know of is he had one affair, which was more lengthy, that was earlier on. And then recently over this past fall he started going out after work every night and not coming home and I saw some e-mails to another woman," Kathryn said.

The woman sent topless photos to Heath, but he said infidelity is not the reason he moved out of their home. Heath blames his strained relationship with Kathryn's daughter Coco.

He said he believes the girl's behavior is "out of control."

"Coco was out of control — screaming, yelling, pushing, slamming doors, breaking things. I believe Coco tried to push Kathryn down the stairs," he said. "I tried to restrain her. She like rips right out of her clothes."

Signs of trouble with Coco started almost immediately after their wedding, according to Heath.

"Kathryn and I have never been on a honeymoon. We went to the hotel in town where we live. A friend gave us a room after the reception [and Kathryn's] daughter showed up at the hotel," he said. "There is no control over Coco."

Point of Conflict: Raising Children

Heath also expressed his frustration over how he and his wife differ on how to raise the children.

"Kathryn and I's argument from the beginning of time has been on how we raise the girls, or how I have no say," he said.

Heath complained during the session that he feels like Coco doesn't give him any respect, but Kathryn countered the argument.

"Don't you earn respect? She tried to say goodbye to him this morning and he just completely ignores her," she said.

A Reality Check

Real suggested the possibility that Coco has some issues.

"If she is diagnostically a kid that is too much for a family to handle, she needs to be in a structured environment that can handle her," Real said.

But the tough talk didn't stop there. An hour into the session Real told Kathryn, "Heath's right and you're wrong."

"There's nothing normal, healthy, forgivable about this kind of a behavior from a kid gone unchecked," Real said. "Your family is a Wild West show. Your kid is out of control and she has been out of control for years. And you have sacrificed your marriage to your child."

Real said regardless of whether Kathryn and Heath stay together or divorce, it is important to "dethrone" Coco.

The session yielded an emotional breakthrough for Kathryn.

"When I had my children I wanted to be the best parent I could be. I mean it was the most important job I'll ever have, so to watch this is incredibly painful," she said.

But Real said the problems between this married pair went beyond the behavior of Coco.

"I do have to tell you sitting here now, if things were exactly where they are at the surface and there was nothing else going on I would have anticipated a warmer reaction," she said. "There's something else going on, I don't know what it is yet. And I don't know if we'll be able to move it or not yet. We'll see."

Tune in to "GMA" Thursday for the second part of this series.