Delta Goodrem & Brian McFadden

Australian singer/actress Delta Goodrem has dealt former Westlife star Brian McFadden a harsh blow by refusing to marry him.

The Irish pop star proposed to his longtime girlfriend last week, according to the Sydney Daily Telegraph in Australia, but Goodrem told him she was "too young" to settle down.

Sources close to Goodrem tell the publication the 23-year-old struggled with her decision because, although she's madly in love with McFadden, she's not ready to become a stepmother to his two young daughters from his first marriage to singer Kerry Katona.

A pal says, "She really loves him very much, but doesn't want to be a mum so soon. It's a huge responsibility and she's still too young."

The newspaper reports a planned vacation in Bali has since been cancelled, suggesting McFadden has taken the marriage snub to heart.