Passage
For this cause shall a man leave his father and mother, and shall cleave to his wife;
For this cause shall a man leave his father and mother, and shall cleave to his wife;
Mark 10:5 But Jesus said unto them, For your hardness of heart he wrote you this commandment.
Mark 10:6 But from the beginning of the creation, Male and female made he them.
Mark 10:7 For this cause shall a man leave his father and mother, and shall cleave to his wife;
Mark 10:8 and the two shall become one flesh: so that they are no more two, but one flesh.
Mark 10:9 What therefore God hath joined together, let not man put asunder.
The verse centers on "cause", "shall", "leave", "father", "mother", "cleave", and "wife". It is saying that the verse draws attention to "cause" and "shall", so its meaning should be read from those terms before moving to application.
The nearby context moves from verse 6's "But from the beginning of the creation..." into verse 8's "and the two shall become one flesh...", so "cause" and "shall" belong inside that flow. In Mark context, the local focus is Christ, faith, and discipleship.
A plain takeaway is to answer the verse's own emphasis on "cause" and "shall" with trust shaped by these words, not by a vague optimism outside the passage.