Intrusive ideation is a coping strategy thought pattern. It is borne out of trauma and is a key component of post traumatic stress disorder. An example of intrusive ideation is when your partner goes fishing, and, before you know it, you picture him falling out of the boat and drowning. You feel the sensations of pain and suffering, his panic, your loss and grief. You imagine calling his family to notify them, the funeral and what you will wear, say and do; the bills; your children; and how you will ultimately cope. Your partner is having a great time, but you are traumatized and feeling panicked.
But if you are not aware that you have just done a little number on yourself in the form of intrusive ideation, and that you just told yourself a story which has traumatized you, then you will feel as if your current state of anxiety has just come out of nowhere. As a result of your story and not because of anything your partner actually did, you may even begin to have feelings of annoyance or resentment towards him, without realizing that you are experiencing those feelings because of your own intrusive ideation. And depending on where you are in your recovery process, you probably have these experiences countless times a day.