For people who practice heirarchical relationships or find themselves in one, whether they are the primary or the secondary, this is a very good read.
(and this is nothing against hierarchical relationships, just relationships that may not be healthy for all involved)
"I have the right to be not just tolerated, but actively wanted by everyone in the primary relationship. I have the right to feel that I am not a problem or a compromise, but that I add value. This may sound unreasonable to some people, but the fact is, if I'm not wanted by my partner's partner, that has an effect on me.
When I am in a relationship with one person, I am in a relationship with all the other people that person is involved with, especially the primary partner(s)--even if there is no romantic connection between us! If I am resented in any way by them, that resentment serves to undermine the secondary relationship and keep it from being 'real'. It creeps into the rules that are created and the definitions that are set in place."