Or in more words:Uncle Pug:sacrifice
Greater love hath no man than this, that a man lay down his life for his friends.
John, 15:13 Sure there are other Scriptures as well as similar phrases from the other religious books throughout the world.
I would imagine that you could put your spouse in there instead of friend, although most happy couples i know are great friends as well as partners. Of course this is the extreme, but at the same time would folks who are in true love lay down their lives for their spouse - this is one criteria by which i guage if i could love someone.