So just to keep this post updated...
Its been 3 weeks now since this thing happened.
Right after this evening she got cold. I mean really cold! At work she always acts like she has something to do, so she does not have to talk to me. I asked her when we will see each other again. She said "I dont know but i will let you know when i have time". She didnt... When i asked her about it she said "Dont get me wrong ok, but we are friends". After that i totally froze her out. No contact for 8 days. No text, no chat, we didnt even see each other at work.
After 8 days she texted me again saying "Hey, are you still alive?"
Texting back and forth a bit... But i asked her right away if she wants to hang out this week. She said yes. So tomorrow im going to visit her at her place again.
What do you recommend me to do? Its obvious that something is wrong and we both know it. And we both know since when...
Should i just keep calm and act like nothing ever happened and try to escalate as usual, and go straight for the kiss?

And what would be the right (alpha male) behavior when she rejects me again and tells me she only wants me as a "friend" again?

Go over to hers, do what you usually do. When you're cuddling go in for the kiss. With your hand just slowly but firmly hold her chin and move head so she's looking at you. Then kiss her. If she fights it and won't kiss you then bail. She's just in it for the attention.

I've only read the OP but from there to me it seems you did what you should have done. She apologized you didn't flipped out so that's that.
Next time you meet do the same thing. Go for the kiss. You know what to do just do it. Everything else is overthinking here.
Personally if I couldn't kiss a girl within a month I would drop her but that's just me. I understand that this is your first kiss etc. so you are excited which you should be cos it's fun
Good luck next time.