Here's my list
1.) ex colleague who was sure she wanted 3 kids but hadn't had any at the time. I had two and when I spoke about any of the realities of parenthood with small DC's she would sort of resist it and say 'oh well mine won't be anything like that.' Her DH was vaguely controlling with money and the last I heard she had given up her job after maternity leave, which had made me feel a bit 
2.) friend who was had dreams of returning to university but things kept getting in the way, I hope she managed to return to study again.
3.) another ex colleague who had a row with her then husband, went on holiday with her mum, met a bloke by the pool, got back home, started divorce proceedings, quit her job and moved across the country to be with him. Apparently they're still together and have a child.
4.) a parent of a friend of DD's. Took her daughter out of school when Covid broke out (weeks before the schools shut) and they never returned. I think her anxiety must have really taken a battering.