@onevoice,
Your question has too many variables:
For example:
- don't you mean 'Why are
some people hardest on those they care about the most?' There are plenty of people who aren't 'hardest' on those they care about
- what do you mean by hardest? Do you mean: they attack those they care about the most; they have higher expectations of those they care about and hold them to those higher standards (where they don't with others); they get picky at any little fault in those they care about the most...there are a lot of meanings for 'hardest'
- by 'those we care about the most', do you mean married family, blood family, close friends, or all as a group...because I've seen plenty of people who hold different behaviour around those different groups...and each can be close.
There's too many variables in your question. Perhaps if your question was 'why do some people constantly fight with their spouse' you might get responses.