For us in our poly family, it was a matter of accretion. Two men, both of whom I love, sharing me; a female friend Clair joining hubby for sex and I discovering my strong Lesbian side with her; Clair getting accidentally pregnant and all of us deciding it was time so I quickly followed; hubby's ex Lora (those two still in love) joining us for sex and ending up staying with the family; us women having more children. For me, I can't say that I love one more than another, but I do love differently, especially between the men and my female family members. If forced to choose, I would stay with Clair and Lora over Red and David. The bond of having children together with the same men, nursing one another's babies, running the household together is incredibly strong.
So we love one another differently, but it is love. (We each have a physical relationship with the other, except the two guys.) All I know is that if I had to do it all over again, I'd do it all over again.