I noticed the same problem with my game except the relationship wasn't lost but all the progress from the previous hour was lost. The game went back an hour or so. Before the recent update fix, when this happened, it was because the game couldn't find the network connection. I didn't get the no network error message this time. This time the game went back an hour to where I had changed a Sims appearance and the relationship event was not finished but it was when I closed the game an hour or so ago. IMHO, something is going on with the game saves. Hopefully, it can be fixed.
Is the story still finished?
Could it be the Sims retired and left the game?
