Lovers may be - and indeed generally are - enemies, but they never can be friends, because there must always be a spice of jealousy and a something of Self in all their speculations.

Summary

This quote suggests that while lovers may often have conflicts and disagreements, they cannot truly be friends. This is because there will always be jealousy and self-interest present in their relationship. The nature of romantic love involves passion and possession, which can create a dynamic of rivalry rather than friendship. Friendship, on the other hand, is built on trust, selflessness, and mutual support, qualities that may be compromised in the intensity of a romantic relationship.