OK so what is different between you and her other partner(s)? With all due respect, and please do not take anything i say with ill intent but, it seems like you are both/all being used for 2 different reasons. If you are in fact her partner then, why need someone else for sex? Are you not enough?
Well, her other partner is a long distance one. They have known each other for about 10 years longer than she has known me and have had a relationship for that long.
She has an emotional bond with her other partner as well as an emotional bond with me. She wants to live with me and share our lives, but does not want to live with her other partner. They would clash if they lived together.
Different people offer different things. I no more expect to fulfill all of her needs than she expects to fulfill all of mine. We are people who enjoy each other's company, are committed to being there for the other person, and *like* the fact that we can love someone else without fear of losing each other.