John Gill Commentary 1 Kings 11:2

"of the nations concerning which Jehovah said unto the children of Israel, Ye shall not go among them, neither shall they come among you; for surely they will turn away your heart after their gods: Solomon clave unto these in love." — 1 Kings 11:2 (ASV)

Of the nations concerning which the Lord said unto the
children of Israel, you shall not go in to them, neither shall they
come in unto you
That is, they should not intermarry with one another; this is to be understood of the last mentioned, the Hittites, who were one of the seven nations this law respected, (Deuteronomy 7:1Deuteronomy 7:3)

for surely they will turn away your heart after their gods ;
which is the reason given for the making the above law, and was sadly verified in Solomon:

Solomon clung to these in love ;
he not only took them, but kept them, and expressed a strong affection for them.