Five years old wisdom: love and kids

My son has a girlfriend. Here is a sentence I hoped I would not write (or think about) for the next 10 years or so. Because he is five and a half. And because he is practically going steady, as they have been friends for more than 2 years now.

They are planning on living in a house in the trees. He recently told me that they want to have only one child, as it is too difficult to deal with two. I wonder how he figured that one out :-D

Then things got weird.

*Disclaimer: the opinions that follow are in no way my own - especially since I suspect the girl's parents might be reading this*

He said that the child will be a boy, but should not be like his little brother - hey, I get you, dude, your brother is at times a major pain in the a#@ - and so are you, but who's judging?
Anyway, back to the weird part: he proceeded to tell me that he wants a boy because boys are more intelligent than girls. To my utter disbelieve accurately described by a "huh!?" he explains that girls believe in princesses. So I am still in my WTF moment and say "but princesses do exist, unlike Transformers and dinosaurs'. That might have been my mistake as he ended the argument with "but dinosaurs existed and Transformers might exist, what do you know?" and moved to another topic.

I conclude that:

1. I am stupid because I read romantic novels and some might mention princes and princesses; 
2. I am an inept mother who convinced her kid that two children are too difficult to manage; and 
3. I failed miserably to prove to a five year old that girls'/women's IQ is not below men's. 

Despite all this, my son has a girlfriend and he tells me he loves me, even if we are both - me and the girlfriend - inferior human (!) beings, so I still believe that all is ok in the world. Just one more proof that love is blind and hopeless.