I understand that you've probably never felt that way with your parents but that situation isn't unrealistic at all? There are many children in the world that deal and suffer from this trauma, in fact if you look it up you will see cases front page.
I'm not trying to be rude but it's actually disheartening to see this issue be called unrealistic. Children who get abused and abandoned by their parents aren't uncommon at all and it leaves a lasting impression on the child and eventually when they're an adult, there's a chance they'll become the same way.
I agree, who knows if the writers have went through a simular situation or know people who have and created this story for them as a mean of comfort.
I could be wrong and it could just be trend with writers to add nuance to there characters.
I will never understand why people give their characters sad backstories but make them so unrealistic, I just can’t take it seriously.