Does your spouse live in the US? Is that why you don't want to apply for an ITIN?
My spouse lives in Mexico, so I filed a 6013g to treat my non resident alien spouse as a resident for tax purposes so that I could get the benefit of filing MFJ. My spouse has no income.
I can't imagine any other reason that your spouse would not have an SS # or ITIN, but if you provide more information you might get an answer more specific to your circumstances.
