The problems involved are as much logistical as legal. If you get married and immigrate to the US and then apply for US citzenship, you can retain your Canadian citizenship. Canadian law specifically recognizes dual citizenship. I am one. The US does not specifically recognize dual nationality, but does not forbid it either, and contrary to information given out elsewhere on this site, will NOT force you to give up or renounce foreign citizenship. However, you do have to LIVE in the US as your actual place of residence between the time you are admitted and when you become a citizen. You can visit Canada, but if you stay there too long you risk loosing your resident alien status. Canadian law is similar. Your BF would have to immigrate to Canada & LIVE there for a period of time (5 years?) before he can apply for Canadian Citizenship. So either the two of you would have to live apart for awhile, or you would have to live in the US long enough for you to become a US citizen, then move to Canada & live there long enough for him to become a Canadian (or vice versa). By the way - none of this is automatic. Just because you are married to a US citizen does not mean you are automatically an immigrant resident - you still have to apply for admission and be approved. It's just easier for spouses of US Citizens. Also, a person married to a US Citizen only has to live in the US for 3 years before he/she may apply for naturalization vs. 5 years for most others. But again, it is not automatic. You still have to submit all the paperwork and get it approved. I am less familiar with Canadian immigration/citizenship law (I was born one so never had to immigrate to Canada) but my understanding is that the procedure is essentially similar.

you might be able to, talk to someone in immigration about it