Unincorporated businesses jointly owned by spouses are treated as partnerships by the IRS by default. Only if certain requirements are met is it deemed a
qualified joint venture and
treated as a sole proprietorship for tax purposes - it isn't an actual sole proprietorship - and may or may not be considered such for other purposes.
It isn't clear Chase includes qualified joint ventures in their definition of sole proprietorship - they may, they may not. But even if Chase accepts spouse qualified joint ventures as "Sole Proprietorship", the OP's wife can't use that option as they haven't set their business up to meet the qualified joint venture exception (among other things, OP and wife are filing separately). OP should consult an accountant if the two wish to pursue a filing as a qualified joint venture for IRS purposes.