Most people would would agree that "love" is a hard word to define, if only because everyone defines it differetnly. Poets have been putting the feeling into words for as long as there has been written language, and while some have done better jobs of it than others, the fact remains: Love is intangible and subjective to the experiences and temperament of each lover.
About the book.
Love is defined as...
1) A deep, tender, ineffable feeling of affection and solicitude toward a person, such as that arising from kinship, recognition of attractive qualities, or a sense of underlying oneness.
2) A feeling of intense desire and attraction toward a person with whom one is disposed to make a pair; the emotion of sex and romance.
3) Sexual Pasion. Sexual Intercourse. A love affair.
4) A person who is the object of deep or intense affection or attraction; beloved. Often used as a term of endearment. The mutual affection and ardor of lovers: passion, amorousness, amour, love, fervor, fire, rapture, ecstasy, intoxication, heart.