It's not okay to cheat on a spouse in life.
Fiona is part of a troubled marriage which has all but run it's course, and she's taken an interest in another man.
Fiona wants to pursue relations with the new man.
Fiona files for divorce before pursuing the new man in her life.
Fiona gets involved with the other man while she is still married.
Fiona's husband is forced to confront why the marriage did not work out.
Fiona's husband discovers the affair and blames her for the marriage failing.