Either way, learn by being told, or learn by using empathy, if she doesn't counter offer it was a no. Once you've had your 3rd no, you're that creepy guy fyi.

I'd give a straight-forward answer to a fellow adult, assuming she or he will take it in a rational and mature fashion. I certainly wouldn't say anything that could be confused on the surface with, "I would, but I can't."

I find this weirdly Victorian. I should treat grown women as fragile flowers that can't take a straight answer?

Put more emphasis on "I want to avoid an awkward situation" and "I don't want to hurt their feelings" less on "but people are adults" and you're pretty much there though.

How is this a good thing? It just confuses people.

It is unfortunate and I sympathise with your hurt feelings, but I think this is just something you should take on the chin.

For a woman, giving the wrong response to an obsessed creeper can cause harm to her career, her body, or her life. (Yes, I am quite aware that women can be creepy and violent. No, it is not a frequent power dynamic in the office.)

It would certainly be nice if we could be honest all the time, but you are demanding far too much in this bargain.