Our Gemara on Amud Beis notes that the crumbling of a home begins at the gate, and Rav Ashi was even able to see this force personified in a vision of a particular demon:

אָמַר רַב אָשֵׁי שְׁמַע מִינַּהּ כִּי מַתְחֵיל חוּרְבָּא בְּסִיפָּא מַתְחֵיל שֶׁנֶּאֱמַר חֹרֶב בַּסַּף וְאִיבָּעֵית אֵימָא מֵהָכָא וּשְׁאִיָּה יֻכַּת שָׁעַר אָמַר מָר בַּר רַב אָשֵׁי לְדִידִי חֲזֵי לִי וּמְנַגַּח כִּי תוֹרָא

Rav Ashi said: Learn from it that when the destruction starts it starts with the threshold, as it is stated: “Desolation shall be in the posts.” And if you wish, say instead that they derive this idea from here: “In the city is left desolation, and the gate is smitten unto ruin [she’iyya]” (Isaiah 24:12). The term “ruin” here is referring to the destructive demon known as She’iyya, who strikes the gate first. Mar bar Rav Ashi said: I saw it, this She’iyya, and it was goring and wreaking havoc like an ox.

What are the “demons” and warning signs that a relationship is doomed? The eminent researcher and Psychologist John Gottman, through his decades long longitudinal studies of couples via thousands of hours of video recording was able to reverse engineer traits of couples that endured versus those who ended in divorce. (Gottman, J. 2000.“The Seven Principles for Making Marriage Work.” Orion.) 

Here are some of his famous findings about behaviors that doom relationships:

• Harsh startup: Difficult issues and topics are brought up with criticism and sarcasm.
• Criticism: Attacking the person instead of discussing the disturbing behavior or need
• Contempt: Cynicism, sarcasm and mockery.
• Defensiveness: Protecting your position instead of being open to possibilities or aspects of the other person’s complaint 
• Stonewalling: Shutting down and shutting out the other person
• Failed repair attempts: When one spouse tries to apologize the other is so hurt or disbelieving that it is consistently rebuffed.
• Bad Memories: Past struggles are not seen as the process to change or part of the journey but instead evidence of the relationship being doomed from the beginning 

The more of these symptoms, the greater probability of divorce. In communities where divorce is considered to hardly be an option, there can be emotional divorce without actual divorce. Just as a limb can be dead but still attached to the body, you can have a marriage that is dead but still legally bound.  The good news is that though some patterns are deeply set and difficult to reverse, they can be corrected with careful, humble collaboration. When they are, many marriages recover.