[posterboy]

> No one can expect that these people will just stop doing it

What about professional attitude? Astronauts sacrifice a lot more than simple lust. Of course, if they went in for a quick fling in the bunks, a break up wouldn't be far around the corner. I'm sure they are aware of that.

On the other hand, in sci-fi depections they send couples and they still break up, but that's more for the dramatic effect. I couldn't imagine myself to allow any distrust in the few people that my life literally depends on.