Kimberly Wyatt was so nervous when her boyfriend began discussing marriage she had to "step outside for some fresh air".

The former Pussycat Dolls star has been dating Kevin Schmidt for several years. She is blissfully happy with him but still feels too young to contemplate settling down.

"I'm not sure if I truly believe in marriage. We've talked about promise rings, but my anxiety levels went so crazy I had to step outside for some fresh air," she told Look magazine.

One of the reasons the 29-year-old isn't sure about marriage yet is that Kevin is a few years younger than her. She has got over the age gap now but when they first got together she found it very hard to come to terms with.

"Yes," she replied, when asked if she's ever had a cheeky Christmas kiss she shouldn't have. "Three years ago when my boyfriend Kevin and I started dating I was scared because he's six years younger than me."