They seem to be a bit more on an equal footing than parent and child is usually shown as. He comforts her as much as she comforts him. I would classify it more as siblings, an older sister taking care of her younger brother.
But she really is acting as a mother.. she's actually raising him...
If this was more of a series that went back and forth between adult him in a relationship and then their cute childhood, I might not have minded as much...
But seeing her actually be a great mom... this is becoming precious...