YesAsia has it. Here's the synopsis:
Directed by Torpong Tunkamhang, the uproarious 2007 Thai comedy 7 Days to Leave My Wife follows a cheating husband with the seven-year itch, and his hilarious efforts to untie the knot. Salesman Yong (Samapon Piyapongsiri) is a typical aging salaryman with a boring job and even more boring wife. Life is a daily drag until he somehow attracts the attentions of sexy colleague Pim (Benjawan Artner)! Next thing Yong knows, he's in a hot affair with Pim. But then Pim slaps down the ultimatum: leave his wife in a week or she'll leave him. Yong starts cooking up different schemes to end his marriage, leading to a barrel of laughs and mishaps, and even some romantic rivalry.
Suwajanee Chaimusik was a Subhanahongsa Award nominee for her role as the wife Ngek. I missed seeing this back in the day, though Coffee Coffee and More Coffee's Peter Nellhaus did and he liked it well enough.