When I was in my early teens there was a teen couple at our hall. I think she was 16 and an elder's daughter and he was 17 or 18 and didn't have connections. What's more he was a foster child (though for several years) of this couple that treated him like an unwelcome child. (Think Cinderella)
From what I could gather from the "special needs" talk, there was some simulated sex (with clothes on) going on. I don't want to sound crude, but the common term we had for it was "dry humping". She was reproved, he was disfellowshipped.
He seemed very repentant. He tried hard, yet the elders found every excuse not to reinstate him. One time he was late because his car died and he walked the rest of the distance to the hall, in winter when there were 3 foot snow drifts everywhere. Yet they faulted him for coming in late instead of giving him bonus points for even showing up. He also ended up working for an elder's cleaning company and was often scheduled to work on meeting nights - also not helping his chances for reinstatement.
Meanwhile, the girl turned 18. At which time, she met some guy at the assembly who was kind of dorky and nerdy and seemed totally out of character for her. She married him 6 weeks later.
To this day, I believe he was disfellowshipped out of revenge from an angry father (and elder) with influence on the judicial committee. And I feel there was a conspiracy to keep him out of the picture until her parents could get her married off to some respectable JW.
He eventually was fed up over the whole thing and never returned to the JWs. Leaving is a good thing, but unfortunately it turned him into a bitter person.
I wasn't there when the "crime" was committed. I don't know who started it, whether it was mutual, who went the furthest, who wanted to the most, etc. So I don't know whether (in JW terms) the punishments were appropriate. All I know is that in later years, she turned out to be the most immoral one, having affairs on her husband. She even came to this ex-boyfriend's house one day to try to finally have sex with him (while she was married0. It sort of flattered him and it crossed his mind, but after a little more time spent catching up and talking with her, he realized what a slut she was and tossed her back out. At least at that time, it was him who had the high moral standards, not her. So I have to wonder whether it was her all along and that maybe she should have been DFed, not him.