Joseph "Ashira" Kohle wrote:

     It was this single-minded purpose that blinded him to the truth. If
she promised Ranma to Shampoo, if Genma did also, he would go. Oh
he might complain and struggle, but in the end he'd go because of his
honor. She remembered his comment made in the tent the night before
fighting Cologne perfectly. She had asked him why it was always
honor. He had looked at her, his eyes clear and serious, his voice even
and calm as he said, "What else is there?"
     Even if he did not make the promise himself, she knew he would not
ruin her word, nor his father's. Cologne had known that also. Her
otoosan did not understand that, but then few understood Ranma, even
those who knew him personally. For many he was a riddle wrapped
within an enigma. About his emotions and thoughts he showed next to
nothing and said even less. Of the many who knew him she had been
the closest for nearly two years, and still she barely knew him. Even
Ukyou knew little about Ranma despite having known him as a child.
     Honor was important to him, as important as breathing. She knew
that beyond a doubt. So her father's words were little comfort and even
less now as she was about to confront im again, go once more into his
room to face emotions that she was still trying to come to grips with.
She opened the door and walked in.

I am not well versed in the honor system but this is not honor it is
black mail.  

-Ramon