The former Beverly Hills, 90210 star and Twilight actor Facinelli announced their divorce last month after 12 years of marriage.
While Garth has confessed that she was resistant to the couple's separation, it has since been claimed that she struggled to accept Facinelli's increasing fame.
"Her career hit a standstill, and she became resentful," a source apparently told Us Weekly.
The insider also dismissed Garth's accusations that Facinelli didn't fight to save their relationship, adding: "He loved being a family man. It was not an easy decision, but they reached an impasse."
Garth has insisted that taking care of her and Facinelli's three daughters is her biggest priority.
> Peter Facinelli: 'Jennie Garth divorce is painful'