I am asking this question for research purposes.

Sweeping generalisation are very difficult to quantify...

impossIble standards for marriage ... am asking this question for research purposes.
Please list three of these "impossible standards."

Faulty premise.
"The politics of we."
"Why does this problem exist (impossible standards for marriage) and what are WE going to do about it?"

Quick answer to your faulty premise: out of maybe 3 billion marriageable people, 500 million have no standards at all, 500 million have impossible standards, and 2 billion have possible standards.
I know this because I know all of them and I asked them.

Impossible people have impossible standards. Stupid people have no standards... the rest fall somewhere in between.

Hahahahaha! Smoothy.