I am a female Canadian who has two kids ages 17 & 19 and I want to move to the USA to be with my boyfriend and eventually get married. He is a dual citizen. Any suggestions as to what the best way to go about this is? Thanks

As you describe the situation, you would need to find a way to get permanent residence. If you were engaged, then you could apply for the K-1 visa. If you were married, the K-3 visa.

Please note that even if you marry now, the older child will not qualify as a dependent even if you are married as that child is over 18 at the time of the marriage creating the stepparent-stepchild relationship.

After you are a LPR, you can petition for the older child, as long as he/she is under 21, but that preference category (FB-2A) is backlogged about 4 years for Canada.

I recommend you consult with an experienced immigration attorney to determine a strategy.

Thanks so much for the quick response. Do you know what would happen if we got married in Canada (he is a dual citizen) and later I went to the USA? Any good sites you can recommend for Canadians seeking advice without having to use a costly immigration attorney? Ie: how to apply for the K1 and how long it might take and is there any cost, etc. etc. Same for the K3...