The most fundamental problem is that you haven’t completely gotten over your girlfriend yet.
Now there is only one plan: find a way to get their family to have their fortune told again. If the location of the fortune telling was chosen by her, you have to find a way to get the address. It is best if she can accept your recommendation. (You have to recommend a relatively famous temple, otherwise you won't be able to convince her to go, and you won't be able to convince her that this time's results can overturn all previous results), and then you go to arrange for a host or fortune teller in advance. I don't believe it's still possible. Your mother-in-law!
If your girlfriend is dissatisfied with you and has no confidence, my friend, you need to work hard!