AMEN, ladyjools. Those terms can be pretty prescriptive and confining for me.
Lately I've preferred to use terms that are more descriptive than hierarchical, like SO (significant other), lover, sweetie, etc. I've always been dissatisfied with relationships that lay out my role ahead of time. I've been very lucky to have the chance to explore a relationship that is about what's right for both of us and for the other partners, not what's right for the structure.