In June of 1945, Arline Feynman — high-school sweetheart and wife of the hugely influential physicist, Richard Feynman — passed away after succumbing to tuberculosis. She was 25-years-old. 16 months later, in October of 1946, Richard wrote his late wife the following love letter and sealed it in an envelope. It remained unopened until after his death in 1988 (source).
October 17, 1946
I adore you, sweetheart.
I know how much you like to hear that — but I don't only write it because you like it — I write it because it makes me warm all over inside to write it to you.
It is such a terribly long time since I last wrote to you — almost two years but I know you'll excuse me because you understand how I am, stubborn and realistic; and I thought there was no sense to writing.
But now I know my darling wife that it is right to do what I have delayed in doing, and that I have done so much in the past. I want to tell you I love you. I want to love you. I always will love you.
I find it hard to understand in my mind what it means to love you after you are dead — but I still want to comfort and take care of you — and I want you to love me and care for me. I want to have problems to discuss with you — I want to do little projects with you. I never thought until just now that we can do that. What should we do. We started to learn to make clothes together — or learn Chinese — or getting a movie projector. Can't I do something now? No. I am alone without you and you were the "idea-woman" and general instigator of all our wild adventures.
When you were sick you worried because you could not give me something that you wanted to and thought I needed. You needn’t have worried. Just as I told you then there was no real need because I loved you in so many ways so much. And now it is clearly even more true — you can give me nothing now yet I love you so that you stand in my way of loving anyone else — but I want you to stand there. You, dead, are so much better than anyone else alive.
I know you will assure me that I am foolish and that you want me to have full happiness and don't want to be in my way. I'll bet you are surprised that I don't even have a girlfriend (except you, sweetheart) after two years. But you can't help it, darling, nor can I — I don't understand it, for I have met many girls and very nice ones and I don't want to remain alone — but in two or three meetings they all seem ashes. You only are left to me. You are real.
My darling wife, I do adore you.
I love my wife. My wife is dead.
PS Please excuse my not mailing this — but I don't know your new address.