One day, he will stop tempting too much to hold on. You will see it, and ask for a reason but he won’t utter a word. A simple smile would be the end of what he had in his heart for years and what you held inside for a while.
You may try to show him exactly how you feel but strangely, it won’t matter anymore. The feeling of wants and have’s would be gone and it would surely put a crack upon your heart.
And behind his smile, there would be several reasons ripping his heart apart, but he will hold back and “let you go”.