Can a Canadian return home for a short period of time after marrying a US citizen

This unfortunately sounds like a bad idea. You and your boyfriend are contemplating an adjustment of status for him in the US, yet thinking of him going home to finalize his affairs in Canada before returning as a visitor and then trying to file for adjustment and advance parole during the time that the application is pending. That plan sounds like preconceived intent to go around the immigration laws which separate nonimmigrants from intending immigrants. You may have problems because of that, and the best recommendation is that he not go home, that you marry and file for his adjustment of status and advance parole, and he waits until the advance parole is approved before he goes back. You can file as soon as you are married and the period of time for an advance parole is generally 3-6 months.  The alternative is that you marry and file for his permanent residence with the idea that he will interview for the green card with the American consul in Montreal.  He may be allowed to visit you for short periods during the time of processing (approximately 1 year) or you can visit him in Canada. Due to the limitations of the Lawyers.com Forums, Alan Lee, Esq.'s (the "Firm") participation in responding to questions posted herein does not constitute legal advice, nor legal representation of the person or entity posting a question. No Attorney/Client relationship is or shall be construed to be created hereby. The information provided herein by the Firm is general, and requires that the poster obtain specific legal advice from an attorney. The poster shall not rely upon the information provided herein as legal advice nor as the basis for making any decisions of legal consequence.