I had a friend who was with her partner for years - maybe four or five years, and they seemed to have a really happy relationship (from outside at least). One day when she was 32 or so, with no catalyst whatsoever, her boyfriend walked out of the flat and dumped her.
She was utterly devastated. She might have even had some sort of minor breakdown. She lost a TON of weight (and was never overweight to begin with). But after a few months, she started to join a few clubs, purely to take her mind off of things and to try and meet new people. It took a little while, but her personality almost completely changed. She just seemed so much happier and more confident, even though she admitted she still felt awful and like she would never find someone else.
I think after a year or so she started casually seeing one of the people she had met in her sports club, but she was wary about it at first, since I think she still had feelings for her ex.
Anyway, they got married recently and I have never seen her happier. She is still much more independent than she was with her ex as well.
She is such a lovely person, and I am really glad it worked out for her.