I don't hold Ron to any standard. I'm just clarifying the definition of "loyal".
I say he's a kind of lifeless character who is mainly there to make Harry look less stupid (he and Harry cheat off Hermione, and he got the worst grades of the three of them). But others claim that Ron's role is loyal friend despite the fact that he leaves Harry flat at two of the most important times of his life.
I agree that Ron's behavior is realistic and forgivable, and it makes him more interesting. But you can't look at the times he abandoned Harry and claim that his primary trait is loyalty. The best you can say about Ron is that Harry likes him and that's enough.
And I'll refer you to Harry's own views on excusing 17-year-olds for being immature regarding his father's behavior and Dumbledore's relationship with Grindelwald.