As mentioned, you’re going to have to define what hard and soft refer to with regard to the sciences; preferably back up your definition; and I would suggest qualifying your further discussion as being with regard only to that definition, with other conclusions being possible with different definitions.
And then you will further need to limit or describe what you mean by psychology. The psychology done by a therapist, or the author of a book on therapy, is quite different than much research psychology which may be highly based on physical measurements of the brain or components of it, e.g. nerves, or for example PET scan measurements under given conditions (with statistics only showing the high degree of accuracy and high confidence in actual difference rather than merely general correlation) and completely falsifiable (provable as untrue, if untrue.)
An enormous amount of what is considered psychology is not falsifiable – if untrue in any of various possible ways, the proponent of the theory offers no experiment that could demonstrate it nor do other authors in the field offer any – and thus not even science in the first place, let alone a hard science.
But that is for you to reason out and provide examples on.
As an example which you should not use: Another post mentioned that Poliquin says that men like flipping channels on the remote because of a caveman past of being used to the images of firelight flickering on the cave walls.
This bit of what many would call psychology is not falsifiable and thus is not science, let alone hard science.
Of course, Poliquin is not a psychologist, so that is not a usable example. It is only an illustration of the general concept, coming to mind only because of having read it here on the forum last night.