A very shy co-worker I am into seems to like me a lot in person, but he doesn't respond much online?

I've liked my co-worker for about a year. I am already living with someone but it's not working out because I am falling for someone else and we have nothing in common any more. (please don't be rude about that, I didn't want to feel like this and I wouldn't ever do anything without finishing things first)

He's 22, I'm 28. In person he stands in my personal space/doesn't pull away when I accidentally touch him or stand really close to him when we are in small spaces due to our job. The other day on the way home we were sat very close talking for 2 hours and he kept rubbing his arm so his hand was brushing my arm.

He sits with me all the time on breaks rather than co-workers that he's actually BFFs with outside of work, and we talk a lot/lot in common. He's shy and quiet around everyone except me, he seems very comfortable talking to me about personal things like a past relationship when he got hurt. And he laughs at pretty much every bad joke I say, even when I'm not talking to him directly. He always seems like he's watching me and listening to everything I say. He smiles and laughs every time I talk to him like we're stupid giggly kids, and he does really nice things like holds doors for me even at the top of stairs and I'm at the bottom. He is the sweetest person I've ever met, I sometimes catch him looking at me and I really wish I didn't feel this way but I do. He knows I'm already in a relationship, or should know because I talk about it openly quite a lot.

However, when I try to talk to him online, he replies slowly, but very short and sweet, then stops replying altogether. It's like we can't actually have a conversation online but in person we don't shut up, and he always seems like he's trying to think of something to say so we can keep talking. I'm really confused by this as usually with shy people it's the other way around and easier to talk online. He agreed to play video games with me online tomorrow but then stopped replying.
A very shy co-worker I am into seems to like me a lot in person, but he doesn't respond much online?
Add Opinion