Story for you chasing.
When my parents had F, she was the model child. Perfect behaviour, followed my mum around, cuddling in excitedly to my dad for stories. But quiet, and subdued. Amd when we turned up? Cue hysteria, tantrums etc.
And when dh dropped 6yo dsd home tonight, she had to be prised off of him whilst having the mother of all tantrums. Horrible for those emotionally involved but entirely normal.
It doesn't make them the fave parent. When O is poorly, he'll be wanting his mum. When he has a nightmare? Mummy. When he wants to tell someone his good news? Mummy. Etc etc.
Glad he liked the bf tho, great news!