Okla. Stat. tit. 43, § 43-129
Alimony without divorce
The wife or husband may obtain alimony from the other without a
divorce, in an action brought for that purpose in the district
court, for any of the causes for which a divorce may be granted.
Either may make the same defense to such action as he might to an
action for divorce, and may, for sufficient cause, obtain a divorce
from the other in such action.