Nebraska Revised Statute 42-374
A marriage may be annulled for any of the following causes:
(1) The marriage between the parties is prohibited by law;
(2) Either party is impotent at the time of marriage;
(3) Either party had a spouse living at the time of marriage; or
(4) Force or fraud.
An annulment will be granted only when one or more of the grounds enumerated herein is present. Guggenmos v. Guggenmos, 218 Neb. 746, 359 N.W.2d 87 (1984).