Some couples come into therapy to heal from affairs/infidelity. The process of therapy can shed light into the "root" of the "problem," as affairs are often a symptom of a more deeply-rooted issue. While one party is dealing with grief and loss, as well as shame, the other party may be dealing with intense anger and obsessive thinking. The journey and process of healing can bring about closer connection and attunement to each other, greater self awareness of tendencies/coping mechanism/"old programming," as well as depth work related to our family-of-origin.
Check out these links which shed light regarding affairs/infidelity and attachment bonds.
http://www.goodtherapy.org/learn-about-therapy/issues/infidelity
https://kinseyconfidential.org/sixtypesofattachmentaffairs/
