United Kingdom, April 18 -- Bjorn Ulvaeus experienced "love at first sight" when he met Christina Sas but he also had "severe problems" with their age gap romance.

The 79-year-old ABBA star fell for Christina - who is in her 50s - following the collapse of his 41-year marriage to his second wife, music journalist Lena Kallersjo, and the couple married last September - but Bjorn has admitted he was initially very worried about the difference in their ages.

He told The Times newspaper: "It was love at first sight, at least from my side. But immediately I had severe problems with myself and the age difference.

"When a man or a woman meets someone much younger and falls in love they think: 'Am I doing the right thing?'"

However, Bjorn dec...