New relationship options

I just downloaded the update and was so excited to check if my sims could finally get married to more than one person but was disappointed to see it's still between two sims only. Was this intentional? I can set my sims to have two or more partners or have partners while married or engaged, but when I switch more than one relationship to married or engaged it switches the other married or engaged sim to a household member. All of my sims in this household have open boundaries and don't feel jealousy over any romantic actions with other sims.