It is not about narrow mindedness or openmindedness
It is all about how much a relationship means to that character from what has been shown in the show and how the story has been told.
Anandi doesn't see J as her ex any more.Even before Shiv entered her life Jagya's importance in her life has declined to bare minimum.
In fact whenever JG came down to BH she only saw him as Singh's son and Gauri's husband and she clearly told Gauri that her Jagya has gone to Mumbai and he is lost for ever.That's why even when ever she saw him in person she never had any FBs of their time together
Only when Shiv started paying attention to her she was reminded of her past with Jagya in connection with that.Gradually with growing bond with Shiv she had stop remembering her life with Jagya because she had been wife of only Shiv in true sense.
Her relationship with Shiv had been so different - she wanted to share everything with him every small moment of joy anxiety fear pain that she experienced
With J she never had that kind of relationship because he made it impossible by not allowing the legal relationship they had into something more.
But if the writers believe that they can convince the viewers that the void left by Shiv can be filled by her relationship with Dsa and J they are fools.Because J and Dsa can only stand by her but can never share her pain or her life.