Do you open your heart easily?

I am an introverted person who keeps all of my problems, feelings and desires inside. I do not talk a lot and make friends with difficulty. I do not like to talk to my friends or coworkers about myself, my family or other personal issues.
Interestingly, when it comes to Skype friends, most of whom are foreigners, I can open my heart more easily. In this way, I can get my problems off my chest. I really feel relieved. It makes me feel better. I hope I could talk to my intimate friends as easily as my pen pals.
I wonder why I could trust the foreigners whom I have never seen well than the real friends or coworkers.

[Good English.  I think the answer to your question is that there are fewer potential emotional consequences to revealing personal details to a remot person that you do not meet face-to-face.  If you tell something intimate to a close friend, there is always the danger that they will judge you and you will feel judged yourself.  There is that danger in a remote relationship, of course, but the effect of a face-to-face encounter is much, much greater.]