If you arranged a therapist appointment to fix your relationship and are now dragging your spouse to therapy, you might as well stay home. Frustration will result.
A relationship won't recover until one or both partners handle outside issues. One spouse being addicted and the other cheating won't assist couples counselling.
Couples therapy requires maturity. Pettiness, name-calling, and blaming aren't appropriate while you and your partner are with your therapist.
While most individuals recognize this, one or both spouses may come to therapy wanting to win an argument (or series of disputes) rather than resolve it.
Trauma and PTSD may be managed with time and treatment, but if it's neglected out of fear, the person will struggle in the dark.
If one or both spouses need to work on themselves, couples' counselling won't function well. We're all bruised. Counseling can only go so far if there's a deep-seated issue.
Agree on what works and what needs work. Both spouses will circle their counsellor to obtain what they want if they have different goals and expectations.
Couples who don't know what treatment or counselling they need might slow development.
Your relationship may require one of various forms of couples' therapy. Each method yields different results.