There is no such thing as unconditional love when it comes to us human and even if there is will be very few and rare. You would be forgiven in thinking what about mothers love to their children which in essence is unconditional to a degree.
From what I have observed the love you get in return from your pets specially dogs are an examples of how love can be unconditional. No matter how cruel you are to them they will still love you and protect you. Legend has it there was a dog who even after its master has passed away and it would not leave the grave side of its master for several years despite being chased with stones and it would come back again and again until the dog died eventually.
This is probably one of the reasons why dogs have done so well as human companion over the mellania for their unwavering devotion and unconditional love. Kudos to dogs and kudos to all those people who love dogs!