I threw mine away. I was so young and stupid. We were part of a flat share at university. He was intelligent and fascinating, I could have listened to him talk forever. I'll call him J.
He fell for me at a time when I was going out with someone that I think (on hindsight) probably had some kind of personality disorder (he gaslighted me to the point where most of my friends, and eventually I thought I was going mad).
I was young and after the above relationship, damaged. Although J was probably perfect husband material, I was looking for thrills and excitement. I wanted to re-experience the wonderful feeling I'd had at the beginning of the very damaging relationship above.
When we'd known each other quite a while, J took me for a day out and asked me out. I turned him down.
I went through one more abusive relationship before settling down with a man who hasn't really made me happy. J got together with a girl when I got together with man no.2.
When I was engaged, I was doubtful enough about my choice to go and check whether J was still with the girlfriend he got together with after I turned him down. He was, so I kept well away. Another friend told me, however, that J told him that on some level, he thought he'd always love me. Anything else would always be second best.
He's still with her. They look very happy. They have two children and though he doesn't have a strong online presence, his children feature heavily. My children don't have a great relationship with their father. He's just not a very loving man.
I just wish I could go back to that day, all those years ago and change my answer.