How do you know a woman with a boyfriend wants you to make a move?

A colleague of mine definitely feels attracted to me. She is interested in who I am, she chases me, her body language speaks volumes and when I talk with another woman she gets jealous and tries to get my attention again.

Unfortunately she has a boyfriend. I don't think she is just doing it for the attention. But how can I be sure her feelings are genuine.

Should I back off and see how she reacts?
Updates
+1 y
Question no longer valid since she was only in it for the attention, typical!
How do you know a woman with a boyfriend wants you to make a move?
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