en_tn/mrk/10/07.md

For this reason a man ... one flesh

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)