If we are talking about Charles and Diana I can't say if they loved each other.
However in some ways I understand what he said. I'm not sure it's possible to really describe true deep unconditional love because it's a very deep personal thing that you know when you find it but putting it into words is very hard because it is so all encompassing and profound. Some things are just indescribable.
Right now I can't say what love is, only what love was. Exquisitely painful overwhelming and filled with a different laughter. Closeness that allowed space, the knowledge that one person changed everything you thought you knew about people and yourself. A sense of strength and a whole new type of vulnerability.
There are many kinds of love. But I think you're referring to the the one that says to you. 'There she/he is, get on with it. Tell her/him how you feel.'