Gwen Stefani believes that her estranged husband, Gavin Rossdale, “had been unfaithful” that led to her decision of ending their 13-year marriage, TMZ reported. The couple announced their divorce Monday, citing irreconcilable differences.

The two reportedly had a troubled marriage but made every effort to keep it going. However, they failed even after opting for “couples counseling,” Hollywood Life reported. The "No Doubt" star was also reportedly unhappy about the time Rossdale spent away from the family home while touring with his band, “Bush,” TMZ reported, citing sources.

 “Gwen and Gavin had been fighting more and more in the past few years. He’s always on the road working leaving her at home to take care of their three boys,” a source told Hollywood Life. “Then when she started working more on her own music and on The Voice they really never saw each other. When they did see each other it was not good.

“It got so bad they decided to go to couples counseling for help,” the source reportedly added. “They have been in and out of it for years and it has helped at times. But the fighting continued and they even had been sleeping in separate bedrooms in the past few months. In the end the distance and trust issues between them grew and grew until they had to split.”

Stefani, 45, and Rossdale, 49, are seeking joint custody of their three children: 9-year-old Kingston, 6-year-old Zuma and 1-year-old Apollo. The couple did not sign a prenuptial agreement when they got married in 2002.

"While the two of us have come to the mutual decision that we will no longer be partners in marriage, we remain partners in parenthood and are committed to jointly raising our three sons in a happy and healthy environment," the two told People magazine, in a statement."To that end, we respectfully request privacy from the media during this time."