it is totally natural to assert yourself at the detriment of others, but I am not sure if it is OK to do it by force without using rational arguments.
People do it all the time; you only have to look at some of the anti-vaxxer threads on here to see people starting from an emotion-derived conclusion and then attempting to prop it up with logic. But it's not just them, of course, I'm sure we all do this sometimes, to some extent.
You were talking about Alices's pre-established conclusion coming from emotional position that Mary's actions are wrong. Where does this specific conclusion come from? What is the origin of such a judgement?
There's no single answer, because the root cause will differ from person to person. You'd have to unpack someone's whole identity to understand why they
feel a certain way about something.