Jesus continues to quote what God said in the book of Genesis.
# For this reason
"Therefore" or "Because of this"
# cleave to
"join with" or "cling to"
# they are no longer two, but one flesh
This is a metaphor to illustrate their close union as husband and wife. AT: "the two people will be like one person" or "they are no longer two, but together they are one body" (See: [[rc://en/ta/man/translate/figs-metaphor]])
# Therefore what God has joined together, let no man tear apart
This statement can be written more explicitly. AT: "Therefore since God joins together a husband and wife, let no man tear them apart" (See: [[rc://en/ta/man/translate/figs-explicit]])