Have you ever thought about having sex in space? What would be more exciting that having your mate doing every acrobatic move you always wanted to do with her/him?
Without gravity everything would be easier and less exhausting, right?
Well, think again, because without gravity moving your hips to pleasure your woman would be pretty difficult, because in a microgravity environment even a slight push would send an object far distant from the point of impact.
Other than this, "keeping it up" would be almost impossible since blood doesn't flow easily like it does on earth. But hey, even if you would get and mantain a good erection, the next discomfort would be sweat: astronauts exercising in the ISS experience a great discomfort because of this, since sweat builds up in layers on your skin because of surface tension and until you dry it off, it will remain sticked to your skin, making you very hot!
The best thing we have right now is a suit that lets you and your mate to strap on one another and levitate together in your spaceship. Quite romantic to think about it, but probably a pain to be realistic.
You know, it's inevitable that one day the first sex experience in space will be streamed on a porn site (and I think PornHub might just be up to something with their funding campaign for a movie: https://www.indiegogo.com/projects/pornhub-space-program-sexploration#/ But, in my opinion we are still pretty far away from this happening.
Humanity will expand to other planets in the "near" future, and it won't do it without the best way to fight the unsustainable burden of existence. It remains to be seen if sex will still be the preferred mean of reproduction, and I think it won't, because having a pregnancy in space would be terrible.
