According to the Oklahoma instructions:
A Resident is an individual that is domiciled in the state for the entire year.
A Nonresident is an individual that was not domiciled in the state at any time during the tax year.
A Part-Year Resident is an individual whose domicile was in Oklahoma for less than 12 months during the tax year.
If one spouse is a resident and the other is not, file a married filing separate return or file married filing joint and all income is taxed as if both spouses are residents. To file separate returns within your account, you can file the federal return and wait for the return to be accepted. Then, change the filing status for the primary taxpayer and file a separate return for the first spouse. The second spouse will need to create a new account and file the separate state return in that account (if required to file).
For more information: