Jessica Simpson and John Mayer have split again, it has been reported.

The couple, who are said to have parted ways several times in recent months, allegedly ended their relationship for good on Sunday (03.06.07).

A source told People magazine: "It has been rocky and it had been rocky, and it reached the end of the road. It is definitely over - the relationship has ended.

"They broke up Sunday night, but who knows what the future will hold. This is the twelfth time they've broken up. Their relationship is volatile. Last week, they felt better than ever. This week, things are rocky. Who knows what the future will bring."

Jessica, 26, and John, 29, who have been dating for the past year, recently spent time in New York and Mexican resort Cabo San Lucas in a desperate effort to save their relationship.

The source added: "They tried to make it work. They dated for a year. They spent time together in an attempt to talk things over. But it's over.

"Every relationship has its differences, but with Jessica and John those differences were starting to become more and more apparent."

A source close to Jessica said: "She loves John but she has to be true to herself."
[Via Jessica Simpson splits again]