Calling Fi "ethics" in English Socionics terminology has led people to focus wrongly on a phenomenon that is determined by all the information elements. "Feeling" is actually a better word for Fi and Fe. Its associations are closer to the actual reality of Fi and Fe.
Example:
Te dominant types are often unaware of their personal feelings (Fi) determining their judgment outside of their conscious awareness. They sincerely believe their judgment is the result of an objective process and are unaware of the influence.
Ti dominant types are unaware of how the emotion they receive from the external environment determines their process of logic or perceptions of categories. They think they are acting based on an impetus that is entirely internal and within themselves when in reality the external feedback they receive emotionally from other people determines their thought.
The reason for the mis-association of Fi with morality is the gravity that people attribute to Fi types. People usually associate gravity and severity with morality.
Fi is just personal internal feeling that isn't exposed openly. Fi types can appear serious to Fe types because of the lack of emotional feedback Fi valuers tend to supply when those types have spent a lot of time in egosyntonic environments.