"During her son's college graduation, Jane hooks up with her ex-husband, Jake, who's married to a younger woman. As if being your ex's mistress isn't tough enough, Jane also finds herself drawn to Adam, a smitten architect."
(Above taken from here).
This was a pretty good movie, with some quite funny parts. Definately not one to watch with the kids or grandkids around though, because it definately deserves the "R" rating imdb gives it.