Ashlee Simpson says boyfriend Pete Wentz is her "best friend". The 'Pieces of Me' singer - who has been dating the Fall Out Boy rocker for over a year - insists she and Pete are soul mates and also claims the musician's constant praise has made her more confident in her work.

Ashlee said: "He's a great sounding board and very supportive. Pete and I compliment each other. We are best friends and we encourage each other. I think that is so important in any relationship - it builds a solid foundation."

The 23-year-old singer, whose third album is due out next year, also revealed starring as Roxie Hart in the London production of the musical 'Chicago' gave her self-esteem a major boost.

She added to CosmoGirl magazine: "There was a time when what people said about me could really get me down. But working on 'Chicago' helped me come into my own. The stage had been a dream of mine ever since I was a little girl, and being able to fulfill it was amazing.

It taught me to be more comfortable with myself."

Pete, 28, also recently described Ashlee as his "best friend".

The bassist said: "We're past the honeymoon period. The truth is, it's crazy to be able to kiss your best friend. It's just a really awesome thing.

"People like to make our relationship seem different than to what it is. People will say, 'No one holds hands that much.' But I'm like, 'Why would you not want to touch the person that you're in love with?' "