Do you think I should have said something when my two friends were arguing?
Why did you not say something?
I didn't want to make it seem like I was taking one friend's side.
It is understandable to not want to take sides when friends are involved. But it is best to speak up when you have something to say, especially if you think it's important.
It makes me mad that I just stood there and didn't say anything.
I can see why you feel that way, but it's normal to be afraid of interfering when others are arguing. Next time something like this happens and you feel you have something important to say, you should say it.