Not as a spouse. Derivative L-2 status is available to a legally recognised spouse and to unmarried children under twenty-one; a common-law or domestic partner does not qualify, whatever their standing under provincial law. She would need her own basis to enter and her own authorisation to work.
Provincial recognition of a relationship does not carry into federal status
Couples who have lived together for years and are treated as partners for every Nova Scotia purpose are often surprised by this. Derivative status under the L category follows marriage, and a partner outside that definition is left to find an independent route: her own employment-based category if she is qualified for one, a student route if she is enrolling, or a visitor admission that permits neither work nor an indefinite stay. Two consequences deserve early thought.
If she has her own profession, testing whether it is listed in Appendix 2 or whether her employer has an American entity may produce a better answer than trying to attach her to Félix's petition. And if marriage is contemplated in any event, its timing changes what is available, which is a planning fact rather than advice about anyone's private life. Where children are involved, an unmarried child under twenty-one of the principal qualifies for L-2 and may study, though L-2 children may not work.