I am lesbian and have never been in an FLR relationship, but twice it has been convenient for me to for periods of some years keep a houseboy servant 24/7.
My experience is that to put a male in his place and train him to be obedient, diligent and respectful, it is imperative to emasculate him by depriving him of all control of his sexuality.
At first, a man thinks that it is exciting to be locked in a chastity device. After a few days, he struggles with it and begs to be released. After a week or two, he is desperately frustrated, but when the chastity device remains locked, he soon surrenders. He becomes soft and compliant, manageable and subservient.
Then he is easily trained and adjusted. I guess that he nourishes the vain hope, that if he is good and pleasing, the chastity device will one day be unlocked, and he will get sex as a reward.
If he is trained well and taught to be ashamed of his masculine sex, if he is constantly reminded that masculinity is another word for primitivity and that the male body and male mentality is crude and repulsive, he gradually becomes happy with being kept in chastity.
He begins experiencing the chastity device as an indispensable part of him, and he begins to fear regressing if the device comes off. He knows that only being in chastity can prevent him from relapsing into disgusting masculinity. This is the worst that can happen to him because he is mentally emasculated and has learned that chastity and systematic suppression of masculinity make him safe.