Pathological jealousy, also known as morbid jealousy, Othello syndrome or delusional jealousy, is a psychological disorder in which a person is preoccupied with the thought that their spouse or sexual partner is being unfaithful without having any real proof, along with socially unacceptable or abnormal behaviour related to these thoughts. The most common cited forms of psychopathology in morbid jealousy are delusions and obsessions. It is considered a subtype of delusional disorder.Overvaluing an idea, which is defined as “an acceptable, comprehensible idea pursued by the patient beyond the bounds of reason. The idea is not resisted and, although it is not a delusion, the patient characteristically attaches utmost importance to investigating and maintaining the partner’s fidelity at great personal disadvantage and to the distress of the partner”. Overvalued ideas are characterized by being existent in the individuals own thoughts, being egosyntonic; meaning that the ideas project the behaviors, values, and feelings that are aligned with the desires and aims of the individuals ego, or consistent with the individuals ideal self-image, the ideas are also amenable to reason but are not resisted. Definition
This disorder occurs when a person typically makes repeated accusations that their spouse or sexual partner is being unfaithful, based on insignificant, minimal, or no evidence, often citing seemingly normal or everyday events or material to back up their claims. Unlike other delusional disorders, people who suffer from this disorder have a strong association with stalking, cyberstalking, sabotage, or even violence.
Risk to children
Children that live in a household with a parent that suffers from morbid jealousy may suffer emotional and/or physical abuse as a direct result of the actions made by the parent. Children may also accidentally overhear arguments or witness physical violence between their parents. They could even be potentially accidentally injured during assaults. The morbidly jealous parent may employ a child or more than one to spy on the other parent. It is not out of the question for a child to witness a homicide or suicide where their parent is the victim. See also
References
Sources
Enoch, D. & Ball, H. (2001) The Othello Syndrome. In Enoch, D. & Ball, H. Uncommon psychiatric syndromes (fourth edition) pp50–73. London: Arnold. ISBN 0-340-76388-4

Further reading
Easton, J.A. ; Shackelford, T.K. ; Schipper, L.D. (2008). "Delusional Disorder--Jealous Type: How Inclusive are the DSM-IV Diagnostic Criteria?" (PDF). Journal of Clinical Psychology. 64 (3): 264–275. doi:10.1002/jclp.20442. PMID 18257054. Easton, J. A.; Schipper, L. D.; Shackelford, T. K. (2007). "Morbid jealousy from an evolutionary psychological perspective" (PDF). Evolution and Human Behavior. 28 (6): 399–402. doi:10.1016/j.evolhumbehav.2007.05.005. Archived from the original (PDF) on 2008-12-02.