I believe the diamonds he references are ‘perfection’ (perfect person/mate) but, he loses interest. Perfection does not hold his attention as he gets close “they start to fade”.
The person he is singing to clearly expected more from his attentions. He regrets failing them, but in the end it was their expectations of him. Never his intent. He is sorry for the pain/upset caused, but he is the way he is. Perhaps even wishing he was different.
I believe the diamonds he references are ‘perfection’ (perfect person/mate) but, he loses interest. Perfection does not hold his attention as he gets close “they start to fade”. The person he is singing to clearly expected more from his attentions. He regrets failing them, but in the end it was their expectations of him. Never his intent. He is sorry for the pain/upset caused, but he is the way he is. Perhaps even wishing he was different.