1 Corinthians 7:17
But as God hath distributed to every man, as the Lord hath called every one, so let him walk. And so ordain I in all churches.
Note 1 at 1Co 7:17: There are so many variations of marital situations that it is impossible to give general instructions that will cover all of the possibilities. Therefore, the individuals must let God lead them personally in their own situations within the boundaries of Paul's previous statements. This is what Paul was advocating here.
Note 2 at 1Co 7:17: Paul was assuring the Corinthians that these instructions, however limiting they might seem, were not unusual. He had given similar instructions to all the churches he oversaw. He was treating this matter the same way that he had dealt with it in other churches.