She is best known for her role as Margene Heffman on `` Big Love '' , and for her roles in films like `` Mona Lisa Smile '' , `` Something Borrowed '' , `` Walk the Line '' , and `` He 's Just Not That Into You '' .
She is best known for her role as Margene Heffman on `` Big Love '' . She also appeared on `` Mona Lisa Smile '' , `` Something Borrowed '' , `` Walk the Line '' , and `` He 's Just Not That Into You '' .