As suspected, James will play the fiance. From the pic in the article, it looks like Jessica's character is attracted to a certain type...
http://www.hollywoodreporter.com/news/james-tupper-joins-millenniums-playing-178694
James Tupper Joins Millennium's 'Playing the Field'
5:38 PM 4/14/2011 by Borys Kit
The actor, best known for TV roles in Men in Trees and Grey’s Anatomy, will appear alongside Jessica Biel in the romantic comedy.
James Tupper, best known for his TV roles in Men in Trees and Grey’s Anatomy, has booked a role in Playing the Field, the Gerard Butler-starring romantic comedy from Millennium.
Gabriele Muccino is directing the project, which centers on a former soccer star (Butler) who is forced to coach his son’s soccer team and then has trouble resisting the demanding yet seductive soccer moms.
Jessica Biel, Uma Thurman and Catherine Zeta-Jones are among those in the cast.
Tupper will play the fiancé of Biel, Butler’s ex-wife, and the soon-to-be step-dad to Butler’s son.
Jonathan Mostow, Kevin Micher and Alen Siegel are producing.
Tupper, repped by ICM, Untitled and attorney Jamie Mandelbaum and will next be seen in Fox’s Mr. Popper’s Penguins, being released June 17.