When you are online, it is hard to solve fights or arguments because of one, people commenting on comments thus adding fuel to the fire, and two, you won't apologise online as your pride is important because it will be shown to the public or friends.

And if you are online, you tend to be more insensitive to other people's feelings, so when you are talking or commenting online, you will be more harsh on what you say and thus starting or worsening your fight with your friend.

No it is not. Because when you don't see the person face to face, you will easily misunderstand the person's tone or intentions. When you are in a bad mood, and that someone talks to you, you will get angry easily because your mind just think that you are talking to a computer, not your friend thus starting arguments easily.