Only a legally qualifying spouse, not an unmarried partner solely by virtue of the relationship, may accompany her in TD status. A TD spouse may study but has no employment authorization, including for seasonal or casual work; any U.S. work requires an independent qualifying category.
Dependent status travels; work permission does not
TD exists so that a professional's household is not separated by the assignment, and it is generous about presence: the dependant is admitted for the same period, may come and go, and may enrol in school or a college program. It is absolute about employment. There is no exception for part-time work, for casual work, for work in the same industry or for work arranged informally through the principal's employer.
A partner who packs seedlings or drives a crew truck for a season is working without authorization, and the consequence lands on both of them at the next entry. If a second income matters to the plan, the productive step is to test his occupation against the professional list now and, if it is absent, to decide whether the household can run on one U.S. income and his continuing Canadian work.
Hypothetical example: a Hope dietitian accepts a hospital contract and her spouse plans to sell specialty baking online from their rented U.S. apartment. The first review identifies every service the spouse would perform while physically present in the United States, regardless of where the customers or business are located.
Canadian incorporation, foreign customers, invoices, and a Canadian bank account do not authorize those services. The household should decide before travel whether the spouse will pause all work performed from the United States or obtain independent employment authorization; TD status itself authorizes no employment.