An obsession is, by nature, disruptive. Symptoms of obsession would include: finding it difficult to concentrate on anything else, feeling like the fantasy is as real (or realer) than reality. If an obsession threatens to interfere with your job performance, or creates problems in your personal life (for example, it stops you from being intimate with people) then you might want to consider seeking out counseling. If the obsession is also accompanied by depression a therapist or doctor might recommend anti-depressant medication.