It can't.
This IS serious. It's simply illegal for a 16-year-old to be in a romantic and/or sexual relationship with a 21-year-old. No one is trying to quash your happiness. These laws exist to keep 16-year-old safe from their inexperience and adults' poor judgement.
I don't mean to offend, but you have to ask yourself WHY an adult wants to date a teenager. By that I mean, why is she not able to have an adult relationship with an appropriately-aged peer?
If it's true love, your everlasting soulmate and all that jazz, then you both will wait 2 years when you can move forward safely.
Answered Nov 07, 2011
Edited Nov 07, 2011