Can anyone explain this to me?

Well, I'd met a problem of relationships between my friend and I in these days. Well, here the problem goes then:
I got a friend, let's name this is person A then. This person A is one of my good friends. And I found something that is really strange, I will getting more and more frustrated while I was talking to person A when I was very upsad or struggling on focusing something. But when I try to talk to the person B( let B the other friends), I will forgotten things that'd happened in an unhappy life times. Why I can't face A just like B(the others)? Can anyone tell me what's the main point of it?
Do I have any prejudice towards the person A???

I wouldn't call it prejudice. The fact is that some people just rub us the wrong way. We are all different so it is just normal to have some of the differences clash. Another thing is that we can subconciously pick up little signals that our conscious mind is not aware of. Person A could have a certain habit that someone in your past had, or an inflection of voice or smell or the quirk of flaring the nose. Any little thing. If this is something that was simular to an abuser (or just someone that you didn't get along with) your subconcious will notify you by many different means, like anxiety or anger or irritation. You may not even have a clue why or what about the person bothers you. The subconcious is a funny thing.
Carrie

<font color=green>Not knowing when the dawn will come, I open every door.--Emily Dickenson