It's clear that almost all of Henchard's misfortunes are caused by his own mistakes; it's hard to blame "fate" or "destiny" for the bad things that happen to him. But at the same time, how much control does he have over his mistakes? In the world of The Mayor of Casterbridge, it seems that characters have very little control over their own personalities. Henchard is born with a bad temper and very little self-control. If he becomes jealous or angry, he'll act on his jealous rage. If his mistakes are a result of his personality flaws, which he was born with and cannot control, how much "free will" can we say that Henchard really has?
Henchard never blames outside forces for what happens to him, because the forces that bring about his downfall are all internal.
Although readers might feel pity for Henchard's misfortunes, they are all caused, either directly or indirectly, by his own actions.