OCD is triggered due to the breach of trust. It has two clear components a) obsessive thoughts b) compulsive thoughts. Compulsive thoughts are the one, which triggers in our mind on its own and we have poor control on their arrival in our conscious mind. We all have such thoughts all the time due to the disturbance in emotional body but since the mind is balanced, as the normal person, we are able to control them and focus on normal life. However, it is an effort. When intensity and periodicity of such compulsive thoughts become higher and reach a critical mass, they turn obsessive and our control on them is now very fragile.
Compulsive thoughts trigger a state of depression (http://nvlife.net/459/early-sign-of-stress-beginning-of-disorder) and that further triggers loss of control on the mind leading it towards obsessive thoughts.
In your childhood, if you saw your parents fighting, you grow up with fragile trust in the relationship, feeling unsafe and always trying to be on guard to protect self. It gets stored in your subconscious as a belief and when you are in a relationship, any single sign of relationship breaking away alarms you by triggering your belief in the subconscious to trigger thoughts to protect your emotional body which does not want to feel unsafe and lonely again.
Being suspicious about your partner and not trusting is the direct form of OCD, however, OCD appears in many mundane tasks such as obsession to clean the house few times a day, repeatedly checking house is locked or not. Such occurrence of behaviors is a case, where a patient does not have enough courage to confront the partner in case of suspicion and driven by self-pity, diverts OCD towards such behavior. Regardless, it remains issue connected with Trust.
Obsessiveness and compulsiveness are two different symptoms of this disorder. Obsessiveness comes from the high ego which has the desire to retain the relationship (survival) and compulsiveness comes from the root cause of trauma (causing insecurity) in the childhood. Hence it is the combination of greater need to survive combined with insecurity. The desire to survive remains the single most positive factor in restoring back the patient in our treatment.
In our research and treatment(http://nvlife.net/category/treatment), this is not considered serious kind of disorder. there is the simple process to reverse the disorder over a period of 3 to 6 weeks to restore their balance of Emotion-Mind-Body and once restores, we heal the trauma of the past to help the patient restore their trust. Simple breathing technique once practiced every day for 18 minutes, after the treatment, ensure that it never comes back and through that patient with some help from family, in few months, begin to vibrate at a different vibratory level and confidence that it will never come again for them.