Katy Perry allegedly split with John Mayer after she "found a phone number" in his glove compartment.
The 28-year-old pop star split from the 35-year-old musician last week after an eight-month courtship.
It had previously been claimed that the separation was due to their hectic professional lives, but sources say Katy was forced to call time on things after she found the woman"s digits in his car.
"John had picked Katy up in his vintage Land Rover so they could visit a Chihuahua rescue centre in the valley," an insider revealed to British magazine Grazia. "When they stopped for gas, Katy opened the glove compartment and found a phone number written on a napkin. One thing led to another and needless to say they never made it to the dog shelter. Katy called her assistant to take her home and they haven"t spoken since."
Prior to meeting Katy, John had a reputation as a womaniser. Despite their turbulent on-and-off relationship it was widely believed that the singer had tamed that aspect of John"s personality. Although it is not confirmed that they have officially parted ways, Katy was apparently shocked enough by his behaviour to finish things.
"Finding the phone number really broke the trust she"d built up with John," the insider continued.
Although it is not known if the country singer did cheat, the suspicion is said to have been enough for Katy.
She split from her husband, infamous womaniser Russell Brand, in 2011 after he reportedly couldn"t stop his flirtatious ways.
Sources say it was a visit from Katy"s father Keith Hudson that first made John question whether he was ready to commit.
"When the couple went to visit her parents in Santa Barbara over the holidays, Katy"s dad took John aside and asked him to take care of his daughter," an insider explained."The pressure to settle down properly really freaked John out."
Katy attended the Nickelodeon Kids" Choice Awards alone over the weekend.