I can imagine The Doctor saying "Her name was Donna, Donna Noble. She was the most brilliant, most clever and most important woman in all the creation, but above everthing, she was my best friend, my partner, my sister... then, I lost her..."<< Did you really have to do that? <<< " I made her forget. She didn't want to, but it was for the best. It'll kill her if she ever does remember. My Donna... I miss my Donna... But she's okay now. She's safe. She's married. She's happy. Without me."
I think the reason so many people didn't like Martha was because she was interested I the doctor. Donna would have been a better companion for the doctor after Rose because she was going to get married and didn't have feelings for the doctor.
I know this is 11 & Amy, but this came to mind: "The 10th Doctor: Donna, I’ve been a father before...// Donna: What?..// Doctor: Lost all that long time ago. Along with everything else. When I look at her now I can see them. The hole they left, all the pain that filled it. I just don't think I can face that every day. When they died that part of me died with them. It'll never come back. Not now."
Doctor: I know. When I look at her now I can see them. The hole they left, all the pain that filled it. I just don't think I can face that every day..// Donna: It won't stay like that. She'll help you. We both will..// Doctor: When they died that part of me died with them. It'll never come back. Not now..// Donna: I'll tell you something, Doctor. Something that I've never told you before: I think you're wrong.