Why is he acting like that

Hi. (Sorry for my english,it's not my native language) We work for the same company. I am 22, he's 29.I don't see him everyday. We're not dating. I know him for about 3 months. I felt something for him from the start. The problem is that I am very shy. I honestly don't believe that the man like this taurus would fall in love with me. One day he's nice and sweet and adorable, greets me with "hey beautiful!" and the other day he acts like if I was nobody important and it makes me feel so small. I told him one's that I find him handsome. He was a little confuse but happy. While he was going home, he gave me such an amazing, beautiful 2-3 seconds glance deep in my eyes lykof he could read my soul. At the beginnin he was smiling at me and trying to have a short conversation. Within few days he started to treating me different. It actually happend when I REALLY had no time to talk to him because of my deadlines. He gave me again 2-3 seconds glance, but this one was weird, said "goodnight" and went sleep upstairs. (I had a night shift and he sleeps in the office sometimes). He became cold and distant. Like if he even had no will to talk to me. It was a little heart breaking. It lasted for about 2 weeks. I was sure that I've made something terribly wrong. I'm a lady and trying to always remember about my pride, feminity and good manners (I am a true leo). Now I am much nicer to him. I even send him a friends request on fb (it was a huuuuge thing to me because I felt like if I am letting him know about my feelings) about a week ago. He didn't accept it yet... Yesterday i sow him again. He tried to have a short conversation with me again asking me about the boring music played in the background. Before he left he told me some kind of compliment (I guess...? when I was texting with my friends on fb)He said that I look nice smiling at my phone. He was so cheerful then like if he was happy to see my smile. I don't know what is going on... I have NEVER been in the relationship before because I never met the right guy. I have no skill in flirting. I am very shy and even distant when I like a guy. It's because of my complexes I guess.

Please help me... what can I do to make him likes me, how to get on with him somehow and know what's going on? Does he like me or not? Should I just give up?

Sorry for my English one's again!!! —