Popular consensus says that its insecure to ask a woman if she has a bf, but is framing the question differently still insecure?

I asked a girl if she was single in a convo. She manages to avoid that question and somehow we end up making out. I have no accountability(I forgot how I managed to do that). The next day, I kiss her and she pushes me away and says, "my boyfriend wouldn't like this." Yet I have never seen this bf. Whatever, abundance mentality and all that good stuff, but I wonder, why did she avoid that question.