Limerence is a term coined by American psychologist Dorothy Tennov. It is not the same as the concept of infatuation. Compared to infatuation, limerence is longer-term and more similar to the kind of intense mental attachment that a mother may have for her child (Wilson 2019).
According to American relationship coach Lee Wilson, limerence could also occur between a person in a stable relationship with another person outside of the long-term relationship. At a biochemical level, limerence can be caused by changes in the levels of neurotransmitters in the brain, including serotonin and dopamine.
In a limerent fantasy, every detail is passionately desired actually to take place. Limerence is considered to be much more intense than simple infatuation or sexual arousal. Limerence can occur at the beginning of a romantic relationship, but as noted by Tennov, relationships are often not long-term when they are characterized by limerence, but not by genuine friendship or companionship. 
Origin of term
In 1979, the term limerence was coined by American psychologist Dorothy Tennov, which appeared as part of her book title Love and Limerence: The Experience of Being in Love. The concept had evolved form her work during the mid-1960s, when Tennov had interviewed over 500 people on the topic of love.
Meaning according to attachment theory
Limerence is not exclusively sexual. It has been defined in terms of its potentially inspirational effects and relation to attachment theory. It has been described as being "an involuntary potentially inspiring state of adoration and attachment to a limerent object (LO) involving intrusive and obsessive thoughts, feelings and behaviors from euphoria to despair, contingent on perceived emotional reciprocation".
- Wilson, Lee. What is limerence? April 9, 2019.
- Wilson, Lee. What Is Limerence? Is It Real Love, Infatuation, Or Something Else? YouTube. Mar 27, 2019.
- Wilson, Lee. Are Chemicals In Your Brain Mimicking Love? July 6, 2019.
- Limerence, Love, and Chemicals. Unfinished Man.
- What You Need To Know About Limerence. Marriage Radio. June 25, 2019.
- Tennov, Dorothy (1999). Love and Limerence: the Experience of Being in Love. Scarborough House. ISBN 978-0-8128-6286-7.
- Willmott, Lynn (2012). Love and Limerence: Harness the Limbicbrain. Lathbury House. ISBN 978-1481215312.