I think you have been told this before. I do understand that many choose to believe it means something
other than that believing men took unbelieving wives, which is numerous times warned against (being
unequally yoked). Solomon was considered the wisest man in the world yet became unequally yoked to
multiple wives and concubines (a thousand total), which caused him to worship idols, something God
explicitly warned him about. When God chose to flood the world, it says absolutely nothings about angels.
It is all about what men were doing, the wickedness of men's hearts, and the evil intentions of men.