How Do I Fix My Relationship With Him?

Hello, I am a 22-year-old girl and I have the following problem: a month ago I got a new job and there I met a very cool colleague, whom I immediately fell in love with. I wondered for a long time how to meet him and finally he met me himself, then added me on Facebook. I liked a few things, he liked me a few pictures. Shortly afterwards, he invited me to go out in the evening with a close friend of his. We saw each other and everything was okay. I decided to show him that I was not indifferent to him and he did not say anything at first. Of course, I didn't overdo it, I was just nice to him. We talked about different topics, laughed, etc. Everything was fine until his friend mentioned that my colleague had a girlfriend who lived in another city. Subsequently, I have clearly made it clear that I have sympathy for this man, because his friend suggested to me that, that he has a girlfriend is very unfortunate for me. I just said that the person in question looked like a very good person, and he didn't say anything. Then, as we were returning home, his friend told me several times that he would soon break up with his girlfriend. Honestly, I didn't know how to react to that, but I already think it was said on purpose. As we parted, the boy in question shook my hand and we parted. On Monday, when I met him at work, he just passed me. Then we met around the coffee machine and I greeted him, and he answered without any emotion. I apologized to him if I had offended him in any way, he said everything was fine. However, the problem is that he behaves as if we don't know each other and doesn't talk to me. I like it a lot, but I don't know what to do. I can't figure out what his problem is. How do I fix our relationship? Even if nothing happens, I want at least friends to stay. How to act, I still apologized, but still, it did not help. Please give opinions and advice.