While deep and passionate thrusting is often sublime during penetrative sex, that kind of movement can create a massive hurdle for anyone who suffers from endometriosis. Endometriosis is a disease where tissue that's supposed to grow inside the uterus actually grows outside of it and attacks the reproductive organs; when a partner accidentally hits or brushes against that tissue, it can cause enough discomfort to ruin the evening. But that doesn't mean sex is totally out of the question. It may just take some readjusting.

Before things get heated, partners should discuss positions and "be willing to experiment and make mistakes," said Irene Fehr, a sex and intimacy coach in the Netherlands.

"Understand that you're going on a journey and figuring this out together. There is no right or wrong answer," she said. "Fear of making a mistake prevents people from trying new things—and that's the only solution here."

Here are five endometriosis-friendly sex positions that you should try next time you want to turn the lights down low.

Modified doggy style