Section 171. When divorce denied, although adultery proved

In either of the
  following  cases,  the  plaintiff is not entitled to a divorce, although
  the adultery is established:
    1. Where the offense was committed by  the  procurement  or  with  the
  connivance of the plaintiff.
    2.  Where the offense charged has been forgiven by the plaintiff.  The
  forgiveness may be proven, either affirmatively,  or  by  the  voluntary
  cohabitation of the parties with the knowledge of the fact.
    3.  Where  there  has  been  no  express forgiveness, and no voluntary
  cohabitation of the parties, but the action  was  not  commenced  within
  five years after the discovery by the plaintiff of the offense charged.
    4.  Where  the  plaintiff  has also been guilty of adultery under such
  circumstances that the defendant would have been entitled, if  innocent,
  to a divorce.