Imagine getting a date with just a few taps of a smartphone, selecting from a large pool of interested people; other idols, models, pretty fans, rich people, actresses/actors etc. Your kakao or wechat becomes your own personal Tinder Platinum Premium+. Of course, we know there's people who take advantage and abuse the system just like like in any other thing, but considering how many groupies exist in the world, they have done a good job at keeping secrets.
Idols are the rock stars of this era. The only difference is that instead of a culture based around bragging about conquests to the public, it's one where it's kept very private among close friends. Don't let anyone fool you into thinking that Korean culture is too conservative or adverse to sex. They do things a little different there but being good looking can open a lot of doors besides employment.
Idols are no different from anyone else. They spend their early 20s finding themselves.