This explains why a man leaves his father and mother and is joined to his wife, and the two are united into one. -Genesis 2:24, NLT
“Haven’t you read the Scriptures?” Jesus replied. “They record that from the beginning ‘God made them male and female.’” And he said, “‘This explains why a man leaves his father and mother and is joined to his wife, and the two are united into one.’ Since they are no longer two but one, let no one split apart what God has joined together.” – Jesus in Matthew 19:4-6, NLT
At the heart of marriage is oneness. It is a unity of mind, body, and spirit for the husband and wife. And it is such a oneness that it disallows any other human party from partaking in it. This unity and exclusivity are the “guts” of marriage, if you will.
Disembowelment is not too strong of a metaphor for the spiritual and emotional reality faithful spouses experience upon discovering the marriage was violated by adultery. Another human being has entered the relationship cutting out the trust and innocent of the marriage union. Lies and sexual infidelity has sliced open the union.
Recovery is unlikely.
Death is almost certain.
I suggest this may be another reason sexual infidelity is named as an exception for divorce by Jesus (see Mt 5:32 and 19:9). Jesus possibly understood such sexual infidelity as an act severing the marriage union. Man (or woman) has decided to separate what God brought together by inviting another human into the marriage bed. So, it makes sense with that context for Jesus to tell his listeners that sexual infidelity are grounds for divorce. The separation through adulterous sin has already taken place…the marriage has been disemboweled by human sinful choice.
My final point in this is such actions harm the adulterous spouse as well. You cannot violate a marriage in this way without harming oneself as you are one with the spouse you betrayed. The knife has been taken into your own guts as well. No one leaves the marriage without deep scars. You cannot violate a spiritual reality without serious consequences. Both parties will need to heal from the adulterous trauma.1
1 A great article that Pastor Tim Keller cites in his book on marriage illustrates this point very well. It is an article written by a lady who was on both sides of adultery. The article is from the New York Times, and it is certainly not from an explicitly Christian perspective even though it reinforces the message not to commit adultery. It is entitled, “A Room Full of Yearning and Regret.” This little article is an excellent primer for someone (pastor or lay leader) who wants to understand the basic trauma and dynamics of adultery.