LONDON: 'Girlfriend' singer Avril Lavigne decided to split from Sum 41 rocker Deryck Whibley because she ''finally'' realised it was a mistake to marry at 21.

Avril Lavigne is getting divorced because she "married too young".

The 'Girlfriend' singer - who announced she was separating from Sum 41 rocker Deryck Whibley last week - has "finally" realised tying the knot at 21 was a mistake.

An insider told People magazine: "She married too young and she finally realised that. Avril realised she needs her own life and needs to explore things without him."

The 24-year-old star married Deryck in a private Catholic ceremony in 2006. They had been dating since 2004.

But even though their three-year marriage is over, Avril has vowed to stay friends with her estranged husband.

In a statement on her website, the star said: "Deryck and I have been together for six-and-a-half years. We have been friends since I was 17, started dating when I was 19, and married when I was 21. I am grateful for our time together, and I am grateful and blessed for our remaining friendship.

"I admire Deryck and have a great amount of respect for him. He is the most amazing person I know, and I love him with all my heart. Deryck and I are separating and moving forward on a positive note."

Deryk was said to be "crushed" when Avril "walked out on him" but claimed their separation was amicable in a posting on his own blog.