Katy Perry splits from John Mayer

Katy Perry has split from John Mayer for the third time.

The 'Wide Awake' singer - who broke up with him after two weeks of dating last August and again briefly in October before reconciling - has reportedly called time on her relationship with the 'Half of my Heart' singer but friends predict it might not be permanent.

A source close to the couple confirmed they recently broke up again and told UsMagazine.com: 'It's sad. It's not over until it's over. You have to see how things play out.'

Another insider hinted that Katy might reunite with him again, saying: 'She's leaving the window open. They have both been so focused on work.'

Katy - whose divorce from comedian Russell Brand after 14 months was finalised last July - was previously said to have told John to lose her number because he could not commit.

But he appeared to change his ways and happily began attending events with the 28-year-old brunette beauty, including the Grammy Awards last month as well as at Barack Obama's second inauguration last November.

They were also spotted on several dinner dates with Katy's parents in Los Angeles and in her native Santa Barbara, where they spent Christmas together.

The duo sparked engagement rumours last month after John presented her with a heart-shaped ruby ring for Valentine's Day.

John recently described their relationship as 'very human' and insisted his romance with the 'Firework' singer felt totally natural.

He said: 'I don't feel like I'm in a celebrity relationship. For the first time in my life I don't feel like I'm in a celebrity relationship. I know it is high profile. It's hard to explain ... For me it feels like something that's very human.'

The 35-year-old guitarist also admitted he had thought about marrying Katy in the future.

When asked if marriage could be in the pair's future, John answered: 'Of course. I mean, I'm still the kid from Connecticut. That's what you do.'