Section 170. Action for divorce

An action for divorce may be maintained by
  a husband or wife to  procure  a  judgment  divorcing  the  parties  and
  dissolving the marriage on any of the following grounds:
    (1)  The cruel and inhuman treatment of the plaintiff by the defendant
  such that the conduct of the defendant  so  endangers  the  physical  or
  mental  well being of the plaintiff as renders it unsafe or improper for
  the plaintiff to cohabit with the defendant.
    (2) The abandonment of the plaintiff by the defendant for a period  of
  one or more years.
    (3)  The  confinement of the defendant in prison for a period of three
  or more consecutive years after the marriage of plaintiff and defendant.
    (4) The commission of an act of adultery, provided that  adultery  for
  the  purposes  of articles ten, eleven, and eleven-A of this chapter, is
  hereby defined as the commission of an act of sexual  intercourse,  oral
  sexual  conduct  or  anal  sexual  conduct, voluntarily performed by the
  defendant, with a person other than the plaintiff after the marriage  of
  plaintiff  and  defendant.  Oral  sexual conduct and anal sexual conduct
  include,  but  are  not  limited  to,  sexual  conduct  as  defined   in
  subdivision  two  of  section  130.00  and  subdivision three of section
  130.20 of the penal law.
    (5) The husband and wife have lived apart  pursuant  to  a  decree  or
  judgment  of  separation  for  a  period  of one or more years after the
  granting of such decree or judgment, and  satisfactory  proof  has  been
  submitted  by  the  plaintiff that he or she has substantially performed
  all the terms and conditions of such decree or judgment.
    (6) The husband and wife have lived separate and apart pursuant  to  a
  written  agreement  of separation, subscribed by the parties thereto and
  acknowledged or proved in the form required to  entitle  a  deed  to  be
  recorded,  for a period of one or more years after the execution of such
  agreement and satisfactory proof has been  submitted  by  the  plaintiff
  that  he or she has substantially performed all the terms and conditions
  of such agreement. Such agreement shall be filed in the  office  of  the
  clerk of the county wherein either party resides. In lieu of filing such
  agreement,  either party to such agreement may file a memorandum of such
  agreement,  which  memorandum  shall   be   similarly   subscribed   and
  acknowledged  or  proved  as  was  the agreement of separation and shall
  contain the following information: (a) the names and addresses  of  each
  of the parties, (b) the date of marriage of the parties, (c) the date of
  the  agreement  of  separation and (d) the date of this subscription and
  acknowledgment or proof of such agreement of separation.