I have a question about a subject in the sentence of "the/the comparative"

I seems to me that the subjects of the former clause and the latter clause are either; (1) same; or different with one of them being; (2-1) "it" referring to time, distance or weather or things in general; or (2-2) a noun modified by a possessive determiner of the subject of the former sentence.

I rarely see the sentence of this structure which take one subject as A (person) and another as B (person).

The more adventurous it is, the more I like it. (NOT The more it is adventurous, the more I like it.) (2-1)
The less I see him the more I like him. (1)
The more he reads, the less he understands. (1)
The older we grow, the wiser we become. (1)
The higher you climb, the colder it gets. (2-1)
The richer one grows, the greater one’s worries. (1)
The less you spend, the more you save. (1)
The sooner they go, the better it is. (2-1)
The older we grow, the weaker our memory become (2-2)

For example, is the sentence written below acceptable?

The happier you get, the sadder I get.

Thank you for your answer in advance.