Who are we?

Usually, we're a combination of 2 species, and [usually] it's one male and one female. Any other combinations would often create social unrest in most countries. On weekdays, you'll only see a handful of us; on weekends, our numbers would increase; it's is only today legions, hordes of us will fester the streets, since it's the only official day so many of us can come out into the light and not be accused of illegal gathering. And it is only today will the almost-cost-next-to-nothing roses [and some other flowers] sky rocket in their costs. Restaurants will most likely be fully booked by us, and swarms of those who didn't make any reservations would patiently wait for seats, creating make-shift road barriers. Most of us would dress smartly today, and some of the female species might be scantily clad, perhaps to make sure her assigned opposite specimen keep their eyes glued on them. It is also today, according to studies, that most of us would journey long and far, to find and taste, what's commonly known as, the forbidden fruit. Unlike the first set of us where it was the female species who tempted the male to eat it, most likely, and most commonly, nowadays the male specimen's the one doing the tempting. Most of the time, the female species, and sometimes even a few male ones, would suffer a relapse of [supposedly wonderful] memories of their previous assigned counterpart(s). So, who are we?

Answer: [Mainly unmarried] couples.

[Duh! (again)]