Any advice on what to do in this situation?

So one of the guys I work with sent me a friend request on Facebook and I ended up confirming it. Then the next day he was messaging me on messenger. I’m not gonna get too deep into what we were talking about but he was saying how he thinks I’m cute and was asking me what my type was and stuff like that. Fast forward to now he stopped messaging me and I don't know if it’s because I was sending him one word answers or whatever the case was. But anyway I’ve been seeing him talking to one of my female coworkers offly a lot and i just felt like it was hella shady (by the way I’m not jealous). And I don’t want to reach out to him first because I don’t want to seem desperate. What should I do?

Any advice on what to do in this situation?
Post Opinion