When all Israel (that is, the northern tribes) saw that Rehoboam wasn't going to listen to their request to moderate work demands, the response was, "Why should we care about David? We have no stake in Jesse's son!" The workers then stoned the work gang leader to death. King Rehoboam fled to Jerusalem.
Israel sent for Jeroboam and crowned him king of all Israel. Rehoboam assembled the house of Judah and Benjamin (the southern tribes) to fight against the north in order to restore his right to rule the whole kingdom.
However, a prophet was told by God to tell Rehoboam and the rest of his people not to make war against the Israelites, "Go home every one of you, because this is my plan." They went home.
These verses are omitted from the lectionary, but I think they help understand the ones that are included. Further, they raise a question of how we decide (realize?) to attribute events to the plan of God.