Question

Why did the Lord become angry with Solomon and tell him that his kingdom would be divided under his son?

Answer 1

According to the bible and Christianity, some of his wives worshiped idols. When he became old, he forgot about god and made sacrifices to idols. So of course, God became angry with him.

source:

1 Kings 11:1–3

"When Solomon was old, he forgot God. His wives wanted him to worship their idols. Solomon did the wrong thing. He made sacrifices to the idols. God was angry at him."

Answer 2

The lord had rules he wanted Solomon to follow, but Solomon began to drift away from the Lords advice and became influenced by foreign wives. Because of this he began following pagan gods which displeased the Lord very much.