In doing a study on divorce and remarriage, I am studying Matt 19:5, which is actually a restatement of Gen. 2:24, "For this reason, a man shall leave his father and mother and cleave to his wife; and the two shall become one flesh."
According to the Merriam-Webster dictionary, cleaving means "to adhere firmly and closely or loyally and unwaveringly". It is linked to the German word: kleben. I use klebich (though it's not really a proper German word) with regards to my 2 year-old... his fingers are often klebich - sticky.
The etymology brings more perspective to our word, cleave, especially when considering some derivatives such as cleavage or meat cleavers. Interestingly, the english word has come to mean both "to split" and "to adhere". This makes simple translation a little more difficult. Apparently, cleave has changed in meaning, so that it can encompass opposite definitions: to stick and to separate.
When there is peace and unity within a marriage, the idea of "cleaving" to one another is not a difficult concept. However, it seems that when life becomes difficult in a marriage, maybe even impossible, suddenly the idea of "sticking together" begins to look like "separation".
This is when it is helpful to go to the original languages. The greek word, cleave, in Matthew 19:5 has the idea of glue or unite. In Genesis 2:24, the hebrew word suggests: to cling, to keep close. Both words are definitely a word picture to help us understand the marriage "unity" that we are to pursue. In both references, the man is told to "cleave". It is an imperative. This is not simply something that happens, but something which he is to do.
We know that we are to pursue this oneness... and we are also warned, "What God has joined together, let no man separate."(Matt.19:6) Therefore, let us pursue those things that "stick" us together.