A little jealousy in a romantic relationship is undoubtedly natural. Certainly each of us has felt an uncomfortable jealous twinge at some point in a relationship. We feel jealous in such moments because of our sense that a cherished connection we have with another person is threatened, and our fear that a loved one may find someone else to replace us. While most people experience jealousy on a very occasional and mild basis, others feel it to a pathological degree. For such extremely jealous individuals, their jealousy almost always leads to the end of relationships.