Is this guy immature or am I just a boring person?

I think he's bored with the flirting. He's probably got things going on in his life that occupy his mind and the conversations on line with you just go the same way all the time. I had a friend who would just message me all the time and say wuu2. I would have to stop what I was doing just to answer her and I'd get really fed up with it. She would talk about stuff I wasn't interested in and I would have to be polite at all times. I did have other people I was speaking to and she would get upset if I didn't come back quickly with answers. It was a bit invasive. I couldn't do anything without her popping up and trying to talk to me all the time. She's got other people she's interested in now and I never get to speak to her. Maybe, you should try to find other people to talk to and other stuff to do on the net. He would probably chat you at some point then to find out what you've been up to, instead of you constantly drip-feeding him all the time. At the moment, he doesn't have to be the one to show interest because you never give him the chance to feel curious. Step back a bit and see what happens. If he comes forward for chats etc, that is great. If he doesn't, then it's not worth the effort.