Started a new job a few months ago and I sit right opposite a good-looking guy. To start with we hardly spoke and that was fine. He then added me on FB and we sent the occasional message once/twice per week. This has escalated, to the point where we can be going back and forth with messages for two hours on an evening/weekend. We speak a lot more at work too. We were joking about one time and I ended up admitting that i liked him. Things cooled off a bit after that so I assumed he didn't feel the same, but then he restarted all the messaging and it got quite flirty. Things upped a gear at work too, with him asking me to come over to his desk to work on a few things (all actually unnecessary) and generally there was a lot of chemistry. We messaged again this evening and I said I'd had a great day, especially getting to sit next to a gorgeous guy (him obviously) and he's cut me dead again. I feel like he leads me on then cuts me down. If he's really not interested, but he knows full well that i am, why does he do this? I need to get him out of my system, but I have to work with him and am literally face-to-face with him every day. Any advice??