'Daisy Lowe and Doctor Who star Matt Smith split up'

Daisy Lowe and Matt Smith have split.

Despite friends claiming they are "besotted" with each other, the model and the 'Doctor Who' actor - who have been in a relationship for 18 months - have reportedly decided to separate after their respective work commitments made it impossible for them to spend any quality time together.

A friend of the couple said: "This has come as a surprise to everyone. It was thought they'd be together for a really long time because they were so into each other.

"They always seemed so happy together. Matt was besotted with Daisy and she adored him."

While Matt has been in the UK all summer filming a number of TV projects, Daisy has been dividing her time between her native country and Los Angeles, where she recently posed nude for Playboy magazine.

The source added to The Sun: "It's really sad that this has happened, but as they're both so in demand at the moment it was really difficult for them to find time together."

However, Matt, 29, is also said to have become increasingly uneasy about settling down and tying the knot with the 22-year-old brunette beauty.

The friend explained: "Whenever engagement and marriage was mentioned he was uncomfortable. He's still a young man and the thought of being tied down was a lot to digest."