Is Russel and Katy's marriage on the rocks?

They've only been married for half a year, but Tinseltown sources claim Katy Perry and Russell Brand are already struggling with their marriage, as they lead increasingly separate lives thanks to their super-busy careers.

With 26-year-old Katy in the middle of her international Teenage Dream tour and Russell busy promoting his two new movies, Hop and Arthur, the pair, who married in India in October last year, is said to have had a series of bitter rows as the time apart takes its toll.

"They're just realising how much work they will have to put in to keep their marriage together," a friend spilled, adding, "Katy knows they can't go weeks without seeing each other… it's not healthy. She's flown twice to see him in between shows. She's exhausted."

Amid claims the pair is already seeing a marriage counsellor as they deal with the pressure of coping with an international relationship, Russell was said to have upset Katy with his comments about monogamy, after he insisted, "It's peculiar and insane to be monogamous, to have just one woman. I keep thinking there must be a loophole in this deal somewhere."

A pal summed it up, "The huge amount of travelling and logistical organising it takes for them to meet up and share some private time takes the fun out of seeing each other."