God mercifully gave Jeroboam further instruction. He was admonishing him to repent! He gave him a couple of miracles, in order to impress upon Jeroboam's mind that he was headed in a wrong direction—that if he did not turn, it was going to mean disaster for himself and for Israel.
God just did not stand aside, wring His hands, and wonder what He could do. He appealed to the man to change.