So my girlfriend discovered her dominant roots this year after being in a vanilla (with kinks) relationship for 5 years. She is 24/7 dom and humiliates/dominates me/teases me in my chastity cage every chance she gets, but once in a while she wants me to seduce her and act like i'm the "man" in the relationship.

We found an exhilarating way to accomplish this:

The dom will tell the sub that she wants him to perform a play for her, she will tell him that he has to be convincing, act perfectly and be ready with his improvised lines. The sub will be judged on these aspects at the end of the session.

"I want you to pretend you have control of this relationship, I want you to act seductively towards me and lay on top of me while making me swoon. After we are done, I will tell you what I liked/disliked.

If you come on too weak, I will extend your chastity sentence; if you come on too strong, I will make fun of your performance and belittle you for thinking you can even be that manly; and if you at any point do something I really dislike, I will grab you by the balls and educate you for the rest of the evening"

Fiddle with it to match your kinks (eg if you are not into humiliation/CBT, find your own punishments), but the main idea is that the sub is only acting at the behest of the dom, the dom gets to have fun humiliating the sub/punishing him based on his performance after the roles are like usual. The sub gets to experience the feelings of being dominated and judged even while trying to seduce the dom.

Win$Win