I agree with you that Americans can seem to be a bit hypocritical about sex and sexuality---we're interested in it, of course, but we seem to be a bit ashamed of our interest in it at the same time---at least that's the public appearance of things. Europeans seem to think sex and sexuality is something to be celebrated and discussed openly, while Americans seem to think it's something best kept private.
Having lived in Germany for 13 years...I offer this analysis.
Yes, there are pregnant teens out there...even as young as 13. The numbers...maybe 10 percent of what you see in the US. So they are heavily doing birth control without a doubt.
No, teenage marriage at 17 or 18...doesn't occur that much. It is probably 20 percent of what the number in the US is. German teens are realistic...they can't get a job that pays for an apartment even as a couple at 18...so if they were to marry...they'd have to live in their parent's house...and they REALLY don't want to do that.
Yes, there are just as many relationship issues as you find in the US...from guys cheating on their girlfriend...to girls dumping guys.
How do the Germans have control over the situation? No driver's licenses until 18. Yep...that fixes the issue of teens running around amok. You are stuck in your village or town...and there isn't any place for you to get into lot of trouble unless the parents aren't home. Most teens will hang out at the local bus stop or park....do their social thing...and by 11PM...go home.
I wouldn't make such a generalization about Europeans vs Americans, since we are far more similiar --- for good or ill --- than we are different.
In all of our nations, two philosophies of sex exist side by side.
On the one hand, the view that sex is predomiantly a matter of durable and creative connection: finding a mate worthy of your sincere self-donation; creative significant alliance between masculine and feminine gifts and genius; growing a family; building lasting bonds of intimacy and trust; linking the genders and the generations; commitment to something enormously meaningful: the Beloved Community "on earth as it is in heaven."
On the other hand, the view that sex is predominantly a matter of individual self-satisfaction: unlinked to family, uncoupled as to gender, insignificant as to heart and spirit, inconsequential in the wider horizon of human projects; unconnected to in-depth commitments (other than --- like disinfectant soaps--- a commitment to antispetic transactions.)
The first has wide scope for both satisfaction and sacrifice; it's worthy of the best of adult investment in terms of love, energy and intelligence.
The second is feeble in generative power and restless in appetite: it comes down to itch, twitch and extinction.