My ADHD partner diagnoses everyone as adhd

My girlfriend and I both have adhd but hers is much more severe. 

She always diagnoses everyone as adhd despite knowing very little about them, even sometimes just hearing someone talk about a person she feels she has enough information to diagnose them. It causes conflict when I sometimes dismiss her "diagnosis" as there is no way she could possibly have attained enough information about a person to make such a call.

Does anyone else find their partner seeing ADHD in everyone and assuming his/her diagnosis is unchallengable ?