Eh my parents and other couples around me act all lovey dovey and that doesn't make me have a "please love me" complex. If that were the case, all single people would have that problem
He also has divorced parents issue you know that right?Not everyone would react to same situations as you fo because we are all have different mental issues and backgrounds,I dont blame you for thinking he is an undamaged child because author made him look perfect boi with perfect family but gave him this kind of personality and mental issues without explaining it single bit.
I just disagree with your initial comment. Imo the problem with Rio is that he was given everything except a stable home/environment to return to. At least from the other stories, it always seemed like he was being tossed around as a kid. His dad was busy, the butler was busy, Kei was busy, Shingo was busy. Sometimes he would be with his dad, sometimes with the butler, sometimes with Kei/Shingo. It still seems to be the case even now. I don't doubt they love Rio and ik they spoil him as much as they could but stability is important to a kid. Coming home to the same place everyday, knowing that someone is waiting for you at home, seeing the same people everyday; that kinda stuff can be important.
I kinda understand Rio when he said hes not number one in anyones eyes,in this story we were always following adults around Rio living in their small worlds and going through relationships,even though each one of them cares Rio,he feels hes always in background