Okla. Stat. tit. 21, § 1083

Any such female person, referred to in the foregoing sections, shall be a competent witness in any prosecution under this article, to testify for or against the accused as to any transaction or as to any conversation with the accused or by him with another person or persons in her presence, notwithstanding the fact of her having married the accused before or after the violation of any of the provisions of this article, whether called as a witness during the existence of the marriage or after its dissolution.