American Idol album Katharine McPhee is engaged, according to OK!

The 23-year-old singer and her actor beau, Nick Cokas, 42, are going to tie the knot (presumably next year). Yes, he is 19 years her senior.

“They’re definitely engaged,” said a source on the set of Kat’s upcoming film House Bunny. “They’ve been talking about it for some time.”

Pictured: Kat and Nick at the 17th Annual Mercedes-Benz Carousel of Hope Ball at the Beverly Hilton Hotel on last October. 20+ pictures inside…

Congrats to the happy couple! More Here! »

American Idol 5 loser Katherine McPhee looks like a winner, catching a flight at LAX airport with boyfriend Nick Cokas on Thursday in Los Angeles.

The super smiley pair got a little lost at the airport and had to be directed on where to go by paparazzi! Watch the video below –