>>I will reinforce that I am not planning on "sleeping together".<<
Husband, Make sure you point out that it's not because you wouldn't want to, because to you she's the most attractive woman on earth (almost any woman would love hearing that!!!). Say you care deeply about her feelings and would never want to do anything that would make her feel uncomfortable.
Andy, It could mean nothing... but I think it's a good sign when they keep old letters. It indicates at least some sentimentality and maybe some possible doubt. When they throw out sentimental things, that's not so good. When my husband moved out he left his wedding ring and some of the things I gave him. This wasn't a good sign!!! But... in packing up some boxes for him, I put in a few wedding photos, old cards I gave him... little reminders. I also transerred some old family videos and gave them to him as a gift!
There is no arriving, ever. It is all a continual becoming.