Guy's Behavior

Does my male colleague like me or just being friendly?

We get along really well and have a lot in common. He's more on the introverted/social anxiety side and I'm more extroverted. Also, he lives with his girlfriend of 4 years who he never mentioned to me at first - i had to find out about her from co workers. Without being arrogant, i do know i am very attractive/been told so and attract a lot of male attention.
Signs i have received from him:

- He texts me if he doesn't see me in the office for a while (vacation, sick etc) to check in/ask me how I am etc.
- Sometimes as soon as i am online, he pings me good morning
- On weekends/Friday nights, he texts me asking what my weekend plans are
- The thing is, when we are in the office, he doesn't come up and talk to me but does so with everyone else, but he messages me on office Skype even when just a few desks away! If i go up to him to talk to him, he keeps the conversation quite short/brief, acts fidgety/nervous and sometimes walks away while i'm talking to him!
- He does look me up to down when he sees me, and i notice he watches me but quickly looks away when i look at him
- There was a point where he started ignoring me completely everywhere out of nowhere (leaving me on seen, not saying hi etc) - especially when i would show a bit of interest back (I am interested but aware he has a long term girlfriend), but now - ever since he found out I'm recently dating someone, he has started messaging me more and in a more friendlier manner rather than being short

What gives?

Does my male colleague like me or just being friendly?
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