From the beginning, it was all part of Rudy's plan. He wanted Rize to stand up for herself and stop being her parent's slave. He wanted her to save herself, so he could save her from her evil parents.
It wasn't about Rize's answer to Rudy's confession, it was about the message, and the courage Rudy was trying to convey to Rize.
Rudy wanted Rize to speak for herself and be honest without being scared of her parents. That's why he hadn't told her anything about the harem yet. Because even if he had, Rize still wouldn't have answered.
She was sacrificing her love for Rudy for Rudy's well-being. She wanted Rudy to live a happy life instead of getting him involved in her matters.
"Just say the word, Rize. You know what you have to say. You know what you want. Just say it, and I will commence it."
