infatuation
Another word for not old is young.
lazy
open relationship
young man
Infant, toddler
young teen means young teens another word tween
Homoerotic. It's another word for homosexual.
This is not really how affairs start. An affair is when the person is committed to another, usually by marriage, and enters into another relationship at the same time. A young man whose eye is on a woman who is already committed or who is not interested has no real choice except to move on. He never had a relationship with that woman, and so it is not an affair in any sense of the word.
Baby, child, toddler or young
kid: youth: todler
observant
A sapling, shrub, bush.