Questions: Guy's Behavior

He seems to really enjoy chatting with me and joking around with me, and seems very relaxed like he can say what he’s really thinking and knows I’m not judging him.
I get the feeling that he wants to get to know me better before having sex again or doing anything else physical. He also seems more relaxed around me after we had sex. I’ve noticed we mirror eachother and it’s like we are in synch with eachother, facial expressions etc. and we even have the same opinions on most things. This is odd because I thought guys usually just want sex?
I can tell he’s still very physically attracted to me because I adjusted my boob and he smiled and blushed and looked pretty turned on.

I’ve been seeing this cute guy around at work.
He works in a different department to me but I see him on breaks, he sits with other people from his department. He is normally deeply immersed in his phone. I’ve noticed a few times that he will gaze at me and when I look at him, he will smile at me while holding eye contact. I’m always the one to look away first (because I am super shy).

A couple of weeks ago, we were walking towards each other in the corridor. He did his usual gaze and smiled at me, then I said “hiya, you alright?” As I passed by. He smiled even more and looked down. A week or so after that, I walked past him while he was eating his lunch and I looked down at him and smiled.

Since then, I’ve noticed we don’t really have those interactions anymore. When I see him, he usually looks in every other direction apart from mine, even when he walks right past me. I have seen him occasionally glance at me when he is in the distance.
We did have another occurrence when we walked towards each other. He smiled and said hiya very quietly and walked off. Today, I was stood behind him at the water fountain waiting for my turn. He turned around, said “sorry” really quickly and walked off. I think he may have left real quick but I was too shy to look at him.

Please help me because I’m starting to feel like I’m repulsive and that he is uninterested.

Do you ask them for advice if you've done something really taboo?

Do you tell them about every naughty thing you get up to

Do you tell them about every woman you've fancied or hooked up with, even if it was wrong?

What else do you tell them?

How come a guy's friends start paying more attention to me and showing more positive interest or joking around more with me, whilst before they didn't pay much attention to me?

Why are his friends looking me up and down like they might suddenly be attracted to me also?