"The one who commits adultery with a woman is lacking sense; he who would destroy himself does it"
This proverb is the plain statement of the case: adultery crosses the line of acceptable behavior. It is unwise. It is foolish. It is personally destructive.
The proverb states that the person who would go outside of the marriage boundaries is lacking sense. The word sense is the Hebrew word for heart or thinking capacity. It is sometimes used of the idea of understanding. The person cannot put it all together what will happen when they do this.
Let me just comment on this straightforward proverb. Adultery in our day and age is seen as no big deal. Everybody does it. The media suggests that marital infidelity is acceptable and even desirable. In fact, the modern media encourages people to think about adultery in the exact opposite way that this proverb does. In the end, one will find that God is right and the modern media and modern ideas of morality were wrong.
Because we have abandoned God's limits on behavior and embraced sexual license, we have emotional and family destruction. The moral line of thou shalt not commit adultery is there because society cannot continue to exist as a healthy enterprise when sexual passions are uncontained.
In our day there is a weak desire to place the limit on sexual conduct right before homosexuality. This will fail; God does not place it there. He places it at marital fidelity. In order for society to have stable families, there must be shame and societal chastisement for those who break down family bonds. The stability of the family must be preserved or the society will begin to come apart. For single people that means fidelity to someone you may not even have met yet. Does it help society when one person saves himself/herself until marriage? Yes. Does it hurt society when one individual is unfaithful to their marriage vows? Yes. The faithfulness of every individual helps the society be a stronger entity. Please do not believe the hype that adultery is no big deal. It is a big deal. It is a big deal for you personally and it is a big deal for our society as a whole.
This particular proverb is about the personal damage done to the individual when adultery takes place. You have taken your ability to think and put it on the shelf. Think through the consequences; it is not worth it.