MOST Professional answer

One tricky but important part is WHEN YOU GET MARRIED.
If you get married before your bf's parents naturlization, you and your bf cannot take advantage of the existing immigration petition your bf filed as son of green card holder. This is because there is no category for married son/daughter of green card holder.
If you get married after parents' naturlization, there is no problem at all. Your bf's existing petition will just be transferred to F3 immigration category. As spouse of your hu*****and, you are beneficiary of the cateory-transferred petition.
I suggest you look for a attorney's advice. $200 for a good advice is a worthy deal.
Another source is 8.CFR (code of federal Regulation regarding immigrations).