For me I think it was between day 25 and 30 first time I played and the special dialogue was already there. I've just check it out again without interacting with her and this time it wasn't there. I did the logic thing (pet her,lovey-dovey,play) and then the dialogue with her appeared. That means you also need her to like you a certain amount. I've bought Death grip drug and did it two times letting her take the lead with cum fully regenerated i.e. 6 and pet her good bunch of times. Also, usually her affection grows whenever she throws a dialogue when making interactions, just so you take it into account. You can even see mental health going up exactly when she says something
In summary: discombobulate perhaps you're missing interacting with her more, that could help you trigger the dialogue