There was war between Rehoboam and Jeroboam throughout their days.
Judah's story and Israel's are intermixed in this book. Jeroboam out-lived Rehoboam, four or five years, yet his history is despatched first, that the account of Rehoboam's reign may be laid together; and a sad account it is. I. Here is no good said of the king. All the account we have of him here is, 1.
Commenting on 1 Kings 14:21-31
there was war between Rehoboam and Jeroboam--The former was prohibited from entering on an aggressive war; but as the two kingdoms kept up a jealous rivalry, he might be forced into vigilant measures of defense, and frequent skirmishes would take place on the borders. Next: 1 Kings Chapter 15
And there was war between Rehoboam and Jeroboam all [their] days. (s) That is, all the days of Rehoboam's life.