Avril Lavigne and Chad Kroeger are engaged.

The 27-year-old singer and the Nickelback frontman are to marry after the rocker proposed to his girlfriend of six months on August 8, Avril's representative has confirmed.

The 'What the Hell' hitmaker and Chad, 37, began dating after first meeting to co-write a song for Avril's forthcoming fifth album.

A source told PEOPLE: ''A romantic relationship blossomed as they spent time writing together.''

Families of both Avril and Chad - who proposed with a 14-carat diamond ring - are thrilled by the news.

The source added: ''He makes her so happy. Both of their families could not be more excited.''

Though the 'Skater Boi' hitmaker has not commented directly on the news, she has retweeted comments of congratulations from fans and replied with a simple ''thanks''.

The marriage is the second for Avril, who wed Sum 41 singer Deryck Whibley in July 2006, splitting three years later.

Following her separation from the rocker, she went on to date reality TV star Brody Jenner for two years until January 2012.

Chad has never previously been married.