don't you have some backup in the autosave section (or quicksave) ?
Viewing post in Goddesses' Whim 0.4.1 - Public comments
I think you can try to undo it if it just a newly saved one (both are newly saved/recent events). Though not that much. And you are unlucky if you did it on the parts that you can't undo like Hunting, Fishing, and some other events.
Lastly, I hope you use every save box, maybe you can still try the "second most recent" unless you don't use it that much, then you are out of luck.