"The English language lacked a noun singular for the state of being love smitten, or having fallen in love, until Dorothy Tennov (1979) coined the term, limerence, to fill the void. It is formally defined as follows: limerence (adjective, limerent): the personal experience of having fallen in love and of being irrationally and fixatedly love stricken or love smitten, irrespective of the degree to which one’s love is requited or unrequited."
January 1, 1970
https://en.wikiquote.org/wiki/Limerence