But technically, Harry wore it too and it didn't make him say horrible things

Because he hardly wore it

Harry wore it a lot, but Ron was also grouchy from getting splinched.

If I remember correctly he did start to become rude but hermionie told him to take it off

*horcrux

I think the horcruxes are like the One ring from Lotr. It takes your wants and desires and corrupts them. Since Ron was already unhappy with a lot of things it was easier to corrupt him.

^Yeah, that's how I always thought of it. Some people are more easily corrupted than others.

He also wasn't very nice in PoA. The movies glossed over it but t was still there. Also his behaviour towards Hermione was bad so many times. The charm only exaggerated his attitude but he wasn't the most likeable person to begin with.

^Yea the horcrux increased any bad qualities Ron had.

Its more and more a obvious One ring parallel lol.

Don’t you dare say he was bad in deathly hallows part 1, because it was the charm thing that was making him rude 

Actually, Ron was bad in Deathly Hallows Part 1, and no, it has nothing to do with the horcrux, it was his own fault, because Harry wore the horcrux more than Ron did, and he wasn't that rude.

As for GOF and HBP, Ron was pretty bad in the Goblet of Fire, but he was actually fine in the Half Blood Prince, he had every right to be angry with Hermione because she hit him several times with a book, then she tried to attack him with birds, and she got very creepy when he started dating Lavender and she was very rude towards Lavender as well.