Separation of family and state

For a long time, the principle of separation of Church and State has been implemented in all Western civilizations, and it has been applauded universally as part of our enlightenment values. What does it boil down to ? Government should have no role promoting or opposing any religion, religious groups or religious values. Its as simple as that.

Why can't we have separation of Family and State? Since when is it the role of government to interfere in personal relationships ? Why should a married man and woman be granted any different status to a single man and a single woman, or two gay men living together, or whatever form of relationship you can imagine. As painful as divorce is, government should have nothing to do with a couple's decision when it comes to forming or breaking personal relationships.

Imagine a scenario where government (with the best of intentions) announces that they have a new "marriage bonus" for fertile young couples so that we can have more children.

They offer a young man a welfare payment if he marries Cindy because she is young and fertile and can have children, but offers no money if he marries Debby because is old and infertile and cannot have children. Shouldn't the man's decision to marry either or neither be based on his own personal values, as to which one he loves ? Why would government interfere in his personal decisions?

Why isn't this principle as popular as separation of church and state ?