He believes she got involved with a staff member at their home and claims there were even instances of inappropriate sexual behavior.
According to Sam, Britney apparently asked one of her staff to film her naked. He also says she had a romantic relationship with at least one male staff member who worked at their place.
From TMZ:
As for how Sam supposedly knows -- our sources say he claims there's footage of Britney and the staffer together in a compromising position.
We're told Britney's in a fragile and hyper-sexualized state, and it's contributed to her dangerous decision-making ... making her a risk to her own safety.
Our sources say Sam acted as a crutch for Britney for a long time, but her recent conduct was too much. We've reported Sam has been over the marriage for a while now, and recent events were simply the last straw, leading him to file for divorce.
Britney is definitely in a downward spiral at the moment.
She's cut off ties with her family and pushed her husband away, leaving her without any support system.
It's quite unsettling to consider that she might end up completely on her own, being left to her own devices.