Wha... huh ... what?

Apparently, not only are Avril Lavigne and Nickelback frontman Chad Kroeger dating, they're engaged.

Those Canadians don't waste any time, do they?

Lavigne's rep told People.com that the two, who have quietly been dating for six months, are engaged. On Aug. 8, Kroeger popped the question, presenting Lavigne with a 14-carat diamond ring.

Lavigne, 27, and Kroeger, 37, first got together in February to cowrite a song for Lavigne's upcoming fifth studio album.

"A romantic relationship blossomed as they spent time writing together," a friend of Lavigne's told People.com.

"He makes her so happy," a family source said. "Both of their families could not be more excited."

It will be Kroeger's first trip down the aisle, and the second marriage for Lavigne, who split from Sum 41 frontman Deryck Whibley in 2009. She dated Brody for two years before breaking up in January, just before she started quietly dating the rocker.