A story is a snapshot of real life, or a good story is. Your audience is not the kindergarten, so we do not require 'and they all lived happily ever after' which is a lazy ending anyway.
Instead, remember the old adage, Leave 'em wanting more!, and do not give in to the temptation to tidy up all the loose ends. Real life continues after we stop watching the participants. So leave the main protagonists in a recognisable place, and leave them alone to get on with their lives
Examples are hard to find because they either work or they don't, and that can be very personal to the reader:
Number 1 tidies up, yes, but it leaves the doorway wide open for the future. There could be a second chapter to this complete short story.
Number 2 gives explicit doubts about what will happen in the future, while giving the reader a satisfactory resolution to the tale
Number 3 is full of promise and expectation for the future
What is really hard is to find a bad one. You'll know it when you try to write a conclusion to every single little plot thread you introduced. We don't care whether Aunt Jane cleaned the sheets and told his mother, nor do we care about Donald's fight with the kid down the road. So they fought, let them get over it!
This section was harder to write than I thought! Maybe I'm trying to tidy up the loose ends.
The opening of a story is obviously very important. "It was a dark and stormy night..." And so on. What is much more important is how the story ends. A story needs conflict and resolution. For the sort of stories we are talking about here, there is too little conflict; resolution is very difficult; and often the stories fade into nothingness.
The stories we are talking about involve the attraction between teenagers of the same gender. Almost always, they are living at home with their parents. They fall deeply in lurve with another boy. It is very rare for parents to accept this, let alone condone this. So how is the ending to be resolved? In most stories, very badly!