For kids, other than science and engineering:
Intimacy
(1) Knowledge. Give knowledge of yourself, what do like, don't like, want, believe, think, plan.
Notice that another person who stands off doesn't give such knowledge.
(2) Caring. Care about the other person, monitor their life, reach out to help them.
Notice how common it is for others just to give you their middle finger.
(3) Respect. Grant credibility, honor, pride, praise.
Notice how others may give you contempt and insults, try to manipulate, take advantage.
(4) Responsiveness. Monitor what they do, listen to what they say, use those two to think about their lives, and do respond appropriately.
Notice how others can not respond, just ignore, turn away.
(5) Affection. It's basic, involves physical contact, especially with facial contact, hand holding, hugging, and apparently is universal at least in all mammels.
Notice how others avoid physical contact.
Uh, as a teen boy dating a teen girls, mostly interested in (1)--(5) or just some anatomy lessons? With some girls, it's easier to have sex or even marriage than much or anything in (1)--(5).
By their teens, maybe boys/girls could benefit from realizing (1)--(5).
That's my "book" for kids!