EXACTLY. this would've WORKED back then, and it must be so confusing for him that it didn't. Men who don't mentally age past their peak never realise that they're no longer in their peak.
Cat was scared that Jon was older than Robb - he probably is
She was scared his mother was trueborn - she was
She was scared Ned favoured him over their shared kids - he kinda did
She was scared he was jealous of Robb - he is
She was scared he wanted to he Lord of Winterfell - he does
She was scared that Robb would favour Jon's claim above their sisters - he does
She was scared his presence could put her children in danger - it does!
Her fear of him is NOT in her head.
I know it's a fantasy show and if I can look at dragons then I can ignore fabric choice, but I hate when you're watching 'period' pieces and u can tell when fabric is synthetic.