For Christians, nothing surpasses the greatest love of all, the love of God, "For God so loved the world that He gave his one and only Son, that whoever believes in Him shall not perish but have eternal life."
Shakespeare immortalised 'undying' love with Romeo and Juliet. Hollywood glamourised it at the 86th floor of New York's Empire State Building where Cary Grant waited (in vain) for Deborah Kerr in an "Affair to Remember", and later with Tom Hanks and Meg Ryan in "Sleepless in Seattle." Of course Bollywood has its share with song and dance amidst coconut trees.
(picture from thestar.com.my)
In real life, there are countless such acts of love too. I'm sure you have heard and read stories of normal average Joes (and Janes) climbing the highest mountain and crossing the deepest ocean to profess their eternal love. Or maybe, they are not normal or average...?
There are two I can recall i.e. here, and here. I am reserving my personal comments on such 'feats'. "To each his own".
What would you do? What would you give to profess your love? Would it be money, time, a precious or expensive present, an act of bravery or sacrifice, your life?