Much as like a 3some is purely about sex, and everyone needs to understand/agree to the ground rules before anyone starts...a potential poly relationship needs to have the same understanding/agreement. It's one thing for a person to say "hey, wouldn't it be fun if we all lived together, sex and everything, and you could be like...a second wife...", but it's another thing for it to be an actual 2+ person relationship.

Do you know what your feelings are on this idea? Do you want an actual "marital" relationship with both a man and a woman? Do you or could you have feelings for both of them? Do they both have the same for you? Perhaps the idea is really more of a live-in sex partner for an "open" couple, or maybe that's really what you want.

Legally, you would never be equal. You would never have access to marital benefits, and when the relationship ends (with one or both partners) you'll like be out on your behind with little concern from the others.

I know not everyone has the same ideas when it comes to bringing additional partners into an established relationship. At one point in our marriage, my wife thought about bringing her "lifetime best friend" into our home, because she had nowhere to go. My wife "loved" this friend much like she loves me, but "in a way that she could never love me". It wasn't about sex she said...more about "matched life spirits". On the opposite side, as a bisexual man, I always wanted to bring a man into our lives. Not for us to become attached to, but literally for my wife and/or I to have sex with whenever we so desired.

So I hope you can see that even before considering the idea of this poly relationship, the basic parameters need to be well established and understood...otherwise it won't be long before one of you says that you didn't understand what it all meant.