Why is this 31/f coworker acting so strange with me 30/m.

Is she just playing games with me or what? What is going on? What is she doing?
So Idk what this girl is doing. We aren't really friends, but maybe she thinks we are Idk. We use to joke around with one another, but since she grew distant. I tried asking her to hang, she didn't respond. So I jsut gave up on her and broke of all contact. Not wishing happy birthday or anything.... I eventually did wish her happy birthday. ... I then had a SB party at my home and didn't invite her. She eventually texted me a few days later saying she was upset i didn't invite her. I treid talking to her over text and she in essence said 'yeah forgot about what i said, you do what you want i take it back.' I asked her 'would u be happy if I invited you?' I just wanted to know what she said and she said 'I mean i only want things professional between us....' I mean i tried then inviting her twice, Second time was to a party at my home and she gave the excuse that she had to get ready for work the next day. Thats bs because she went out the previous day for a small event....

I mean on one hand, shes upset because i didn't invite her. Then I confront her and she takes it back. Then I try asking her to hang twice and she Both said she was busy.

Why is she doing this? She says she wants things professional, but doesn't act. Why doesn't she just say, 'stop texting me, we aren't hanging out period.' Doesn't a professional relationship mean not to interact with me via text or anything.. /??