Caleb, as portrayed by Michael Easton, has so much passion, intensity, and depth that probably no mortal can match his love. In his doomed romance with Livive, I think he knew that as much as he wanted and loved her, she would end up shattering him. There's a sense of futility--she can't truly love him as he loves her and will only end up abandoning and deceiving him like everyone else. But he hopes for the impossible because he can't stop loving her with all his soul--he can't compromise or restrain his love.
Michael Eastpm was perfect as Caleb--the intensity is overhwelming, even in a still picture; onscreen he is completely overpowering--his eyes, his mouth, his voice, his hands, his gestures. I think a lot of people are afraid of intensity, including Livvie. People don't want to be blasted with the power of a feeling; they erect all these defenses to keep from feeling too much. At work, for example, a couple of my colleagues, seeing Michael Easton's picture, told me his "intensity" disturbed them. Blandness, it seems, is preferable to most; that's why Rafe and the angel storylines on Port Charles are so popular.