Canadian, Partnered Up With US Citizen
In the United States, members of an LLC are not required to be U.S. citizens, so forming the LLC with you and your partner listed as the owners would not be a problem in whichever state you decide to register in. (For online businesses, states such as Wyoming and Delaware are commonly the top choices due to their business-friendly statutes).
Once you have the company formed, you would then draft the company's Operating Agreement, which will specify who owns the company, and what percentage of the profits, responsibility, liabilities, etc. designated to each individual member.
Regarding the taxes, while we are professional incorporators, we are not professional accountants. That being said, I would suggest consulting with a professional accountant who is familiar with taxation of foreign individuals owning assets in the US.