My wife gets to pick the pics of her we share in here. Same already mentioned reasons: being identified, having the pics re-posted elsewhere, jobs, family, self esteem, etc. She's not too keen to share the most explicit ones. We're still working on her exhibitionist side to come out and play!
I also have pics of my previous girlfriends, which I treasure. Even if married and after so many years, even if the things ended up the way they did, I have trouble sharing their pics for a few reasons: I promised I wouldn't and I can't ask them now. I wouldn't like them to be recognized either (well, a part of me would like it, but you know what I mean). At some point we trusted each other, those girls were very important to me, and I treasure their pics and their memories, as part of my life. Honor? nostalgia? respect? stupidity? You call it.
Specially with my first girlfriend: Highschool sweetheart, short and slim with light brown straight hair, beautiful smile, small perky boobs and the cutest round ass. White skin with freckles, dark-green eyes. We dated since we were 17 until 19 in the early 2000's. At the time I was into film photography so she was my muse and model! Somewhere in my old bedroom at my parents', there's a few negatives and prints, most of them in B&W that I personally developed at school, and one color film that was a drag to develop back in the day! Also a couple of miniDV tapes and CDs with scans and a few early-era-digital photos. Most pics are of her nude posing in very tame positions, but the videos i remember were quite hot and sometimes explicit. My first love and my first sexual experiences, are all in there to keep, and I guess they're only that relevant or important to me: The excitement behind the story and memories is something I cannot share.
I wonder if she remembers I have those pics and vids from almost 20 years back. I wonder if her husband knows!