In 2006, a Navy Seal jumped on a grenade to save 2 of his buddies. You can read the story here.
This is certainly an amazing sacrifice that should be an example to us all. However, I have never heard of anyone jumping on a grenade to save the enemy. That would be absolutely crazy.
When Jesus jumped on the cross, He did not do it for His buddies, those who loved Him. He gave Himself for His enemies, those who were hostile to Him and wanted to destroy Him. I was His enemy, launching a full-scale attack against His authority. What do you call such love? The Gospel!