Charles Spurgeon Commentary Jeremiah 3:7-8

"And I said after she had done all these things, She will return unto me; but she returned not: and her treacherous sister Judah saw it. And I saw, when, for this very cause that backsliding Israel had committed adultery, I had put her away and given her a bill of divorcement, yet treacherous Judah her sister feared not; but she also went and played the harlot." — Jeremiah 3:7-8 (ASV)

But she returned not. And her treacherous sister Judah saw it.

And I saw, when for all the causes whereby backsliding Israel committed adultery I had put her away, and given her a bill of divorce; yet her treacherous sister Judah feared not, but went and played the harlot also.

Some cannot be kept back from sin by the punishment of others, but they run into the fire in which others have been burnt, and so they aggravate their sin.