Katherine Heigl stars as a compulsive bridesmaidshe cultivates friends for the sole purpose of joining their wedding parties. Secretly in love with her boss (Edward Burns), she has to negotiate an emotional obstacle course after he proposes to her dependent and popular younger sister (Malin Akerman). Meanwhile a wedding reporter (James Marsden) has been dogging the older sister’s steps, writing a story about her compulsion. For most of this romantic comedy, fatuous contrivances run neck and neck with what seem to be authentic observations about repressed sibling rivalry; some of the latter are too painful to be funny, and eventually the contrivances win out, but the cast keeps it all watchable. Anne Fletcher directed a script by Aline Brosh McKenna. PG-13, 107 min. (JR)