If you give someone extremely mixed signals, she or he will end up ignoring you just for self preservation. I'm sure you meant no harm, but If you try and see things from the girl's point of view, you'll understand why she must be very confused and hurt. She would have no idea why you took her out only to then ignore her, and when you started with the attention again, she couldn't trust that you wouldn't just start ignoring her again for no reason. That doesn't necessarily explain why she's now you. Perhaps you are unintentionally pressuring her because you want to make things better, or perhaps she has heard that you acted on your co worker's gossip. I think the best way to move forward is firstly for you to know what you want from this girl. If you are pursuing a relationship, then probably the best action to take would be to apologise, explain that you were confused about your feelings, and ask her out. If you just want to ease the tension in the office, be casually pleasant to her from now on, and leave it at that. I hope you manage to patch things up so that you can enjoy a peaceful workplace.