My daughter experienced the same thing with one of her closest friends who was a bridesmaid at my daughter’s wedding. For some reason she couldn’t have cared less about the wedding and suddenly, at the start of the festivities in the evening told someone else, not my daughter, that she had to go home because her dog was ill.
It was so strange and unfathomable,that they haven’t talked since. She has no idea that my daughter has just had twins and my daughter doesn’t want her to know.
She just accepts that the friendship is over but has no idea why.
As you say Jenarry, she wonders occasionally, but it’s her friend’s loss, not my daughter’s.
Get on with your happy life without her.