To be a gentleman or not to be a gentleman? Why do girls like guys that treat them like he's doing them a favor by being with them?

I was raised by a household of women my father left when I was a young boy never really knew him. My point to that is I learned to have manners and respect towards women starting at a very young age. In my teens I read a lot of literature Shakespeare, Edgar Allan Poe, Robert Frost etc. All that being said I am a true gentleman to a lady from my past from the education I gained by reading those great literature works.
Here's my question,
Why do I see so many beautiful and bright young women allow themselves to be treated like a subpar humanoid from someone I view as a subpar humanoid. Basically why do girls like guys that treat them like he's doing them a favor by being with them?
To be a gentleman or not to be a gentleman? Why do girls like guys that treat them like he's doing them a favor by being with them?
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