It hasn't been working for 70 years because that is when the sexual revolution started replacing it. There was also an attempt to break it in the 20s, but the depression reeled that back.
Now concerning the matters about which you wrote: “It is good for a man not to have sexual relations with a woman.” But because of the temptation to sexual immorality, each man should have his own wife and each woman her own husband. The husband should give to his wife her conjugal rights, and likewise the wife to her husband.
The same thing that has worked for all high cultures, heterosexual marriage.
It hasn't been working for 70 years because that is when the sexual revolution started replacing it. There was also an attempt to break it in the 20s, but the depression reeled that back.
-1 Corinthians 7:1-3