What is the meaning of [A good man is hard to find]

A modern-day proverb, bemoaning the difficulty of finding a suitable male partner.

This phrase was coined by Eddie Green, as the title of his song A Good Man Is Hard To Find. This was composed in 1918 and first offered for sale as a piano roll in the Fort Wayne Journal-Gazette on 12th December that year (just in time for Christmas – a bargain at 90 cents):

A good man is hard to find
You always get the other kind
Just when you think that he is your pal
You look for him and find him fooling ’round some other gal
Then you rave, you even crave
To see him laying in his grave
So, if your man is nice, take my advice and hug him in the morning, kiss him ev’ry night,
Give him plenty lovin’, treat him right
For a good man nowadays is hard to find, a good man nowadays is hard to find.