Interesting thread topic - and I've been mulling over for a few days books that would fit your rarified "kino" and am left perplexed.
My take on Ada or Ardor, which I read earlier this year, was quite different from yours. The young adolescent discovery of eros seemed a relatively minor stratum of this work covering as the book did the whole lifespan of the major characters. To me the focus of the book was Nabokov's usual beat, the Russian prince libertine, teenage girls, incest, butterflies and arboreta, growing old - a fantasy on the lives of the privileged few that pervades most of his work.
The 60s dreamscape? Sure it was written in the late 60s, but in my view Ada wasn't a 60s' fantasy - Nabokov had been exploring all this for decades. He's the classic ephebophiliac (for the female sex)
But have you read Robert Rimmer's The Harrad Experiment? I haven't read this since the 60s when it was written but it made a profound impression on me about the "free love" prevalent in those times and, although not such an idyl as Ada and maybe the characters are not quite young enough for your criterion, but Harrad explores the 60s' sensual development of young people in a speculative, uptopian manner which you may find of interest.
I'd be most curious to read of any other anon's suggestions for this thread, too.