(I'm going to put the photo at the bottom just in case someone clicks on this by accident because the photo is a huge spoiler)

Dear Bucky, 

I'm so sorry. This is all my fault. I made a promise and I broke it. I promised I would keep you safe and now I had to watch you die for the second time. I'm so, so sorry. I don't even know what happened. It all happened so fast. I never got to even say goodbye. Feeling you die in my arms was the worst thing I have ever felt. We were supposed to get married. I was supposed to propose to you after it was all over. I had it all planned out. We were going to move to Brooklyn in a small apartment and we were going to get a dog and maybe even a cat and then, later on, we were going to have a baby. We were going to raise a child together, Buck. I was going to retire. We were going to live a normal life until this asshole Thanos came along. And now we can never have that. I know that you would never want this, Buck. I know we don't trade lives. But you have so much more life left in you than I do. I want you to find a man who will love you as much as I do. I want you to have pets and kids and I want you to be happy. If being domestic like that isn't what you want, then take up the shield. My shield is yours. You're the only person I trust enough to bear it. But please try the domestic life first. For me. Don't let this destroy you and don't feel guilty. This is my choice. I love you so much. You deserve a second shot. Use it wisely. Goodbye, Buck. I'll see you when you're time comes. And do not make that sooner than it needs to be. 

Forever and always,

Steve