Inside Britney Spears and Sam Asghari's Relationship 'Issues' and 'Cheating Allegations' That Led to Split

Britney Spears and Sam Asghari's marriage is over. In the wake of the news that the couple has called it quits one year after they tied the knot, a source tells ET about a cheating allegation that may have led to that decision.

"Britney and Sam have split. She's adamant she didn't cheat," the source says of the 41-year-old singer. "The two haven't got along for a while and it finally came to an end after a major blowup."

Another source notes of Spears, "She has been denying any cheating allegations and going through a lot of emotions."

Meanwhile, another source says of the allegations, "Sam believes that Britney cheated on him. He believes he caught her in a lie and it caused him to be done with the relationship."

According to TMZ, which was first to report the news of the split, the decision to end things came after Spears' husband confronted her over rumors that she had been unfaithful, leading to a big blowout fight.

"Britney has not been doing well regarding her current situation with Sam," ET's second source says. "She is hurt because the situation brings up old feelings for her."

The second source adds that the breakup "is the last thing" the pop star needed, as her children -- Jayden James, 16, and Sean Preston, 17 -- recently moved to Hawaii with their father, Kevin Federline, amid the devastating wildfires. The situation, the source says, has left Spears "worried."

"She has been trying to get back on her feet and be healthy emotionally, physically, and mentally," the source says. "Britney has people by her side and her immediate circle is there for her. They are rallying around her."

As for Asghari's mental state, an eyewitness tells ET that the 29-year-old actor "was out by Sunset Plaza in West Hollywood on Saturday, August 12, with two other guys and he was not wearing his wedding ring." The eyewitness adds that Asghari, who has reportedly already moved out of Spears' Thousand Oaks home, "seemed like he was in good spirits" during the outing.

Even so, a third source tells ET, "Sam feels like he has gone above and beyond to support Britney and be there for her and like it is never enough." However, from Spears' point of view, she "has the tendency to feel like she isn't being prioritized by Sam at times," a fourth source claims.

That same source notes that "Britney and Sam have had issues on and off as a couple since before they were married."

"Their issues tend to get worse when they are away from each other and spending time apart," the source says. "Their arguments have led them to become unhappy at times in their relationship. They are also on different pages when it comes to their future as a couple, which has been a point of contention."

ET has reached out to reps for Spears and Asghari about the split news.

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