Because we can’t know who is working on something or not, we have the chiyuv of being dan l’kaf zchus. Its not outrageous to assume that someone is working on something, so shouldn’t we? Being dan l’kaf zchus is a bigger thing than many ppl realize…
I have also learned abt giving mussar to others. You can ask your Rav for his say, but I learned that nowadays, tochacha isn’t that simple. I was taught to only speak up if #1 there’s a realistic chance that the receiver will accept it. That means knowing them, and being close and caring. It means not speaking up if you are upset or were hurt by them. An example I recently heard was, being in a store, and someone taked something out of your cart. If you don’t care to give it up, but feel the person needs a lesson in behaviour, you shouldn’t speak up, because you were insulted.
Based on what I learned, I think for us to judge OP or make assumtions or accusations would be unfair and wrong. Whether or not the woman was allowed to speak to the friend abt the tznius (NOT abt hurting the relative), and whether or not the OP should have gone out are halachic shailos, but not for us to judge…