Can my boyfriend adopt my son even though we aren't married & the father to my son isn't on the birth certificate?

The bio father will have to be notified and asked to sign over his rights to allow the adoption. After that if he will not sign, you go to court, if he does not appear you will normally get permission to adopt. If he fights it most likely he will stop any adoption. Many times the father if he is not part of the child's life signs to stop paying child support.

In some states a boyfriend, if it is a long term relationship but many US states still require the word MARRIED and for at least one year.

I agree -- most states require you to be married before the boyfriend can adopt the child. Even if the father isn't on the birth certificate, the same applies.

If you plan on marrying, and your boyfriend/fiance wants to adopt, you will have to find the father of your child, and get him to sign over the rights tot that child. A DNA test may be required depending on the specifics of your situation. After the rights are signed over, then you (your husband) can apply for adoption of your child.

Good Luck,