Along with perfect trust, one of the central philosophies of Wicca. Perfect love corresponds to the elements in one's life and environment attributable to the Goddess. It can be summed up as unconditional acceptance of everything for what it is. People (or things) are who they are.
It doesn't mean that Wiccans prance around saying that they love everyone. (That is reserved for the Purple Dinosaur.) You can hate someone's guts and still perfectly love them. When you perfectly love someone, you accept the whole of their being, but you don't have to agree with it, as long as you accept that they're in your life to teach you some sort of lesson. Maybe that lesson is to avoid that sort of person, because they're not worth the energy you spend in conflict with them. Maybe it's to teach you tolerance. Maybe it's something else. Conversely, simply loving someone doesn't mean that you perfectly love them, if you don't accept the whole of their being, and not merely those parts which you like.
Perfect love is something to be striven for, but is unattainable on this plane of existence. We are human, and therefore are not perfect, but the effort to exhibit perfect love leads to our spiritual growth.
"In perfect love and perfect trust"