The pregnant Colorado mother found dead along with her toddler daughters last week suspected her husband of cheating on her, a close friend said Monday.

Shanann Watts had recently “entertained the idea” that her husband, Chris Watts, was unfaithful, because he’d been acting strange, her pal Nickole Atkinson told ABC’s “Good Morning America.”

“He wasn’t being the loving Chris that he normally was,” she said. “He wasn’t touching or hugging or doing stuff like that. He wasn’t being as attentive to the girls as he normally is.”

The dad of two was also being bizarre when his wife, 34, and their daughters, Celeste, 3, and Bella, 4, vanished on Aug. 13, Atkinson said.

“He just kept saying that he didn’t know where she was and that she was on a playdate. But he couldn’t give us the name of the friend,” she recalled. “Anyone in their right mind will start piecing things together and think something had happened, but you don’t want to go there. You want to believe the best in people.”

Atkinson became concerned for her friend because she wasn’t responding to messages and had missed a doctor’s appointment where she was going to hear her baby boy’s heartbeat.

She said she was the last friend to see Shanann early Aug. 13 until her body was discovered three days later in a shallow grave on a petroleum refinery’s property, where Chris Watts had worked. Their children’s remains were found submerged in oil in tanks also on the property.

Watts, 32, was arrested Wednesday night and police say he confessed to the murders. He was expected to be charged Monday.

“I mean couples or families have their issues, but not to where it justifies what was done,” Atkinson said.

Atkinson wasn’t the only friend Shanann Watts confided in about fears of her husband cheating. Her pal Amanda Thayer told CBS News on Friday: “It came to her mind that possibly he could be cheating.”

Despite their issues, Watts never talked about separating from her husband or leaving him, Atkinson said.

“She very much loved her family and wanted to be a family,” she said.

But on the day Shanann vanished, Chris told Atkinson that they were going to separate, she said.

“I basically told him that that wasn’t my [concern] at that particular moment because it wasn’t and that their business was their business, that they would either work it out or they wouldn’t.”