In fact I wouldn't be furious, we wouldn't be together.
I had a relationship with someone, before I married, who had one child and I only had the one.
We spent time together as a unit, he spent time with my child alone and I spent time with his alone. We also both made sure our children had time with their respective parents alone.
My ex on the other hand pandered more to his current girlfriend and her younger sibling, who she effectively raised, palming my child off.
The relationship ended but it was a great blended unit. Robyn posts everything and is never shown to do anything with Ivy independently, never shown to do anything with the two girls on their own and then takes their dad's time away from them.
It's three children's lives, two of which are old enough to understand and be seriously effected by all these changes. There are whole categories of ACEs attributed to the emotional upheaval and this is how she portrays it to the world.