Ron is traitorous and disloyal to Harry, his main job was to make sure that Harry does not make more friends at school.
'Whatever house I am in, I hope she's not in it' - quote from Ron.
When you first read this quote in Harry Potter and the Philosopher's Stone book, you may not feel strange, but looking at the whole series, you may end up on questioning yourself why did Ron say that.
The easy explanation is that Ron does not want to be friend with Hermione.
Looking in the later chapter of the book, you will see other quotes supporting this
'It's no wonder no one can stand her, she's a nightmare, honestly' - quote from Ron.
From here, we can see that Ron was using every opportunity to try and annoy Hermione.
I don't know why Hermione refused to speak to Harry and Ron since Harry's broomstick has arrived, but obviously Ron have done more than that to cause Hermione to burst into tears, and thinking she's friendless.
Because Harry was not brought up in a proper environment, he goofed off with Ron so much instead of spending more time with Hermione.
It seems that Ron was trying to do as much good as possible to Harry when they have saved Hermione from a troll.
What have happened in the third year?
Hermione caused Harry's new broomstick to be confiscated.
Then Ron suspected that Scabbers was being eaten by Hermione's cat after Harry got back his broomstick.
Did Harry really want to leave Hermione alone from that time onwards?
Not exactly, he asked Hermione about whether she have been to the Quidditch match that they won against Ravenclaw, and Hermione did not refuse to answer him.
Did he stood up for Hermione in front of Ron?
No, simply because he does not want to ruin his relationship with Ron.
If Harry have been brought up in a proper environment, he would have, least of all, realised that it is not his business whether Ron's rat has been eaten by Crookshanks or not, and he could have stood up for Hermione.
What happened in Harry's forth year?
Harry's name came out of the Goblet of Fire.
Did Ron believe that Harry did not enter the Tri-Wizard Tournament himself?
No, he did not at first, he turned back and apologized later.
Did Hermione believe that Harry did not enter the Tri-Wizard Tournament himself?
Yes, she did.
What have happened in the Seventh book?
Ron abandoned Harry and Hermione because he thought that Harry knows what he is doing. He was the first one to sign up to go with Harry to search for Horcruxes.
Did Hermione abandon Harry? No.
Therefore, we can say that, Hermione Granger was Harry's truest best friend. If Harry have been brought up in a proper environment, he could've thanked Hermione for everything she did for him.
Ron is traitous and disloyal, his main job was to ensure that Harry does not have any more friends in school.
If Harry was brought up in a proper environment, he could have stood up for Hermione in front of Ron when Ron was trying to drag him away from her, and then he and Ron would easily break up, and he could've thanked Hermione for everything she have done for him.
Hermione Granger is Harry's truest best friend,