The Opposite of Opposite

I remember hearing in school that one of the few words in the English language that is its own antonym is "cleave," which can mean either to adhere to or split from. Surprisingly, I learned today that one of the synonyms for cleave is ALSO its own antonym: "laminate," which can mean either to split into layers or to put together in layers.

Why all the confusion in our language about whether things are coming together or coming apart. (And, now that I'm up to my neck in this, why would you use "come" for both together and apart?)