Mature but eternal love!

Dear (name),

The time span between youth and old age is much shorter than anyone imagines. Anyone who does not enjoy entering the universe of the elderly is a creature unworthy of his own youth. We only die when the heart stops loving, not just when it stops beating.
I hope you feel, even though I am a mature man, that I am not afraid of old age. I still have a lot of strength in my chest to love! We have a big age difference, but I believe in your discernment when assessing the circumstance.
As I love you so much, I know you will never bring about the premature death of my dreams. You've already proven that you love me too, and the simple difference in chronological age will never be an impediment for this love to increasingly thrive, grow and bear fruit.
Brave human beings were buried for lack of support from true love. They practiced psychological euthanasia, denying the possibility of a happy and full survival. They simply let themselves feel useless, denied themselves love.
I know that with us, this will never happen. I trust your affection and your intelligence. We'll be happy for ever. Our love will be eternal.