I had same problem
I talked to her amd next time i needed to invite her but that day was Saturday so i waited till Monday and when i went to invite her i faced same problem that you have
I load my save and didn't talk to her at all about date and this stuffs (I waited for Monday and start her quest in that time and after i talked to her for date everything was solved
I think its a bug that happens when you need to interact with character but because it was weekend and you passed the day taht you should talk to her game crash because of it
I suggest you to do what i done
(I didn't encounter any bug like that with is really good)
