Sometimes “primary” and “secondary” are the only appropriate terms. My lover is a married man, and his wife is a cuckquean.
She will always come first, and I will never rise above second. Not only are we all comfortable with this arrangement, but it helps keep things simple and clear.
And as a Kept Woman, being secondary to your lover can be extremely arousing.
For more about what I mean, visit my blog. http://KeptClose.blogspot.com/
Secondary isn’t always a negative thing. Being secondary can be beautiful.