BTW, Portuguese has a full range of words to describe the several levels of relationship between two people.
The most common one, if the couple is not married at all, is
namorar indeed. But is perfectly possible to say that a married couple is
namorando when they (finally!) can stay alone and have a romantic scene.
For "to flirt", we have
flertar, which, by its turn, is derived from the English word.
Paquerar, however, is more widespread.
From some time on, young people start to have quick affairs for fun. This includes from just kissing to have a sex night, but usually not more than a couple of times, and sometimes with several dates in a single night
(one a time, of course - that isn't an orgy
). The verb we use to describe such a behaviour is
ficar (with sb.).
CC: guilon kafetzou