She's just being annoying. Like she didn't want you, but she doesn't like that you're giving attention to other people now. Keep ignoring her and go about your day. If it's really starting to get annoying call her out on it.
As a 25-29yo adult, You might find other places to hang out. Preferably where she isn't.
Just continue to ignore her. I don't get why you would ask four times. After the first time you should have gotten the hint. Right now it just seems like she wants to play with your emotions. Just don't give her the time of day.
Why the hell did you ask her 4 times? She clearly doesn't likes you, and likes to see you down, or probably she is just trying to lead you on again then tells you no after getting enough attention. Just ask her to leave you alone.