Idk but I think it's because we're mad, we start to think about things that happen/happening now ( even though it might've not even happened) so we just out burst on people, cuz our mind is just like
'We're fine? We can talk to people, but let's see if they'll realize we're mad and if they don't, let's burst, and if they do discover that, and try to comfort you, let's burst at them.'
But then when we come back into the right mind of things, we realize what our mind has done, and we just think 'oh god, brain you're a hurtful meanie!!!' Then we try to fix things but because we're stressing out we immediately think 'oh no there is no way in fixing this, it's doomed!!' Then we become sad. But I bet in the morning when you try to fix it again and explain what just happened, they should forgive you, and if they don't, I got a bowl of your favorite ice cream, a ton of awesome female character stuff, and a set of ears to listen to you. :3
That's just what I think, I hope it helps, sorry if it didn't :(. But if you ever need to talk, I'll just be over here, on my banana phone, reading your amazing fanfics, and watching Netflix day and night.