To couples: You're not gonna promise to each other that you will not disappoint one another, because at some point you will. What is important is you don't go away, you don't escape, you don't leave one another just because you were disappointed. That's the meaning of fidelity.
claddagh ring... the crown means loyalty, the heart means love and the hands mean friendship. If you wear the heart towards you (crown pointing down when looking at it) it means you're taken. If you wear the heart out it means your own heart has not yet been won.