At The Office

I’m working in a successful company almost 3 years. Every day we are in a hurry to make some money for the company and be on the list of top 5 successful companies in my country.
I have different colleagues, men and women. I hang out almost with everyone and everyone like me as a person. I must admit that we have some few handsome men and one of them is all the time flirting with me. I like him too, but the only thing that I do not like in him is that he is totally uncommunicative person. He did not say a word to me from the moment when he came in this company. I know some personal stuff about him, only because one of my closest colleagues is hang out with him. Otherwise, he is so quiet and mysterious at the same time.
One time we even went out with my colleagues after the work time and he was there. He was talking with others, but when he needed to talk with me he was quiet and in one moment he even ignored me. I was really surprised and even a little angry because I did not know what happening and why he is acting like that with me. I was wondering my close colleague, if I did something that I was not aware about, but he said that everything is fine and maybe the guy is just shy when he is next to me.
Even this fact was weird, but at the end I decide to accept it. After some months of this his time in this company, he get a better position in the company because of his hard work. We had a little party in the office to celebrate his success and then everyone went home.