Here’s an arrow to Valentine’s hearts: Sex for Americans has become rarer and riskier. Not only have our frolics grown less frequent, they’re more fraught due to a resurgence of sexually transmitted diseases — some scary.

Although it may be part of a global trend, this phenomenon has gone from the positive (fewer unwanted teen pregnancies) to a growing concern (plunging fertility rates and even depopulation).

What’s with our bedroom doldrums? How can you safeguard your health and well-being when acting on one of humans’ most powerful and important drives?

Let’s have a little grown-up discussion about sex.*