Looks like you are just out of this in time.
As a neophite at this & man, my 2 cents worth:
I expect the poly relationship has to go slow, at first, perhaps without sex & work toward all three enjoying each other's company & caring about each other equally first. If the caring is really there in the first relationship, One member shouldn't have to "go along", to accomodate another.
If you continue in poly perhaps you find an established couple you like equally, before going forward. Does that make sense??