I've gotten really fed up with the child's attention at work, though

Hey girls, I have a problem. There’s this guy at work who keeps coming up to me, asking if I want to grab a coffee and stuff. At first, I agreed out of courtesy, but he’s really overstepped his bounds now. He comments on every story I post, and I feel like I’m always being watched in the office, which is really bothering me. However, he seems like a good guy. I'm scared that if I complain, he might lose his job, but I can't work like this either. What do you think? Should I be firm with him or just keep ignoring it?