Everything is fully consensual

 
 
As well as the Knight setting what he is willing to do, with both Telling Others and Shared Activities he can set what he is allowing his partner to do.

Thus others can't be told about their practicing Devotional Sex unless he is willing for this to happen, and with Shared Activities his Princess can only do things with others that he is allowing her to do, and these things must be done within the ways that he has approved.

This is necessary because it is the relationship which is of prime importance, and so he is not restricting her from doing things as her Knight but as her partner.
 
 
As well as being consensual, most of what happens should be done to enhance mutual happiness ie it should be things that you both enjoy.

Mutual happiness is also increased if both are willing to sometimes do a few things which will make their partner very happy even though it isn't something they are keen to do. So she can have her Knight do a few things mainly to make her happy, and when she feels like it, she can have something happen mainly to make him happy.
 
 
It is safe to explore any of these enhancements because at any time he can change his mind about what he is willing to do or have happen, and, if she no longer wants to do something then she can use the control he has given her to end the activity and decide that it won't ever happen again.