(one-itis; n: A mental state a person reaches where they can only think about "one" specific person belonging to the opposite sex "or same sex if they are homosexual". What makes this different from an acceptable romantic-state is that the feelings and emotions are uni-directional and the other person does not feel the same emotions/feelings, therefore one is placed/trapped in this trance where it becomes an obsession and cannot focus on other romantic/sexual partners around them "often times, above and beyond the quality of the person they are obsessed over" and they start to ignore friends, family, and the world around them, this "one" person quickly becomes the center of their universe.)
GrkScorp