That was a horrible, horrible thing. Especially after reading The Pandora Principle, or the very similar DC comics' Saavik origin story.
Wisely is right because that kid was a minor....and Robin Curtis...well...wasn't. I don't like those implications so...I'd rather believe his chi was focused (That's what she said)
Saavik didn't do it with Preston. He had a crush on her, but it never went anywhere - she didn't return it, although she did befriend him after Spock explained to her what a crush was. Saavik and David were indeed having it off though. And Spock looked to be at least 17 when he and Saavik were into it...
About 80 years after being teacher and pupil, and both without romantic partners in all that time in between, they decided it was... logical to become partners rather than remain alone. I know some human teachers and students who impatiently waited about five years till they thought that society might accept their decision.
And the great thing is she never had to tell David she cheated on him. Cause that Klingon f*cked him up pretty good.
Well here in the UK it's 16 so maybe on Vulcan it's about that age. Oh I don't know, he's Star trek character. They have a way of coming back when you least expect it.