This, basically. The showrunners don't have an accurate human understanding about growing as a person and they think Sadie is the most realistic depiction of it.
In the beginning, my wife and expected that Sadie and Lars would be the token hetero couple that worked through Lars' hesitance and ended up truly appreciating each other. That episode about the baking really seemed to be a step in that direction but NOOOOOP.
Apparently queer cartoons feel no obligation to represent heterosexuals and hypocrisy is one of my biggest personal triggers.