There are signs when these civilizations come to an end
I was 17, girlfriend was also 17.
Only with a girl.
Secondly, in the U.S. age of consent is enforced state by state. It ranges from 16 - 18, most states have it at 16 (I think about 30 out of 50 as of this writing).
California is one of the few that has it as high as 18. However, that's the state where most U.S. entertainment - including adult entertainment - gets produced, so I think pornography laws are enforced nationwide based on Cali's standards. But don't take my word for it, I'm not 100% sure. Also, it's still illegal to take minors over state borders for sexual purposes, even if the state you visit has you both at a legal age. I think you both need to be certified residents of the state. Each state also has it's own set of rules regarding deviations such as close in age exceptions, age difference, et cetera, et cetera, some strict, others not strict, some straightforward, others utterly confusing, and some states have it somewhere in between. To be honest, it's a real f***ing mess. Pun intended.