You would have to ask a person who has done that, but I'll speculate that how the father feels trumps the life of his daughter. That's the number one side-effect of religion that I don't like. Truth takes a backseat to how you feel.
And the people who commit honor killings probably think the same about you - that you are letting your own feelings trump the truth.
That they are acting in line with truth, and you are the weakling ruled by your feelings.
Your absolutist approach to the topic of truth vs. happiness proposes that you know the truth, and if anyone who thinks differently than you, does not know the truth and is merely indulging in their feelings.
Although I suppose you see no problem with that ...
I will guess it's identity. When something is a part of your identity (no matter how false the underlying premises), any attempt to change that will nearly always be perceived as an assault on your identity (which people often equate with their very lives). In other words, it's less painful to cause pain to others than to try to uproot your identity.
Same goes for you.
I don't even know what that phrase is supposed to mean, but faith seems easy. Just unconditionally accept whatever you want. There is not much 'will' to it in my opinion.
??
"Just unconditionally accept whatever you want."
That sounds like a nonsensical idea, not like something actionable.