Because hate's just the flip side of love. Like heads and tails on a dime. If you don't know what it feels like to love someone, how would you know what hate is? One can't exist without the other.
The quote reflects the intertwined nature of love and hate, suggesting they are two sides of the same coin. It implies that one cannot truly understand or appreciate one emotion without experiencing the other. Love and hate are deeply connected, existing in a relationship where the presence of one enhances the understanding of the other.
In essence, the quote from Jodi Picoult's "Lone Wolf" highlights the complexity of human emotions. The idea is that love enriches life, but it also makes individuals vulnerable to hate, as the depth of feelings can lead to opposing emotions. Thus, this quote captures the duality that characterizes passionate relationships.