You must determine for yourself if this woman falls into the category that I described, for it certainly appears so.
In other words, does she want sex for sex sake AND with you because she loves you...the answer is no already, for a person who loves another would NEVER go beyond the first indication that something was amiss.
This appears to be more of what I described, for indeed there is nothing more agressive than a woman of any age that either wants sex in order to abase herself due to a terrible self image problem, and /or to get even with her parents........Dad particularly because she FELT abandoned and knows that the worst thing a girl can do to a father is to sully and dirty up that which is her most prized possession, her womanhood. Or get pregnant, or if inter racial sex would be the worst thing she could do to hurt parents, then that is exactly what women do.
Women are beautiful to know, but believe me they can be more cruel than men by far and when they are "spiritually immature", they can become unbelievably wanton.
A real man should help to protect a young woman from these deep seated emotional problems, for indeed they will do the most puzzling and degrading things when they are immature in that way, and often they become what they accuse men of ...( a lie, by the way)...and that is a "user".
Women know that they can control a nice or weak guy totally by how they manipulate their body.
Avoid that like the plague, for your heart will break, for a nice guy simply cannot fathom the reason for his kindness being used against him.
Basically, you answered your own puzzle by your final sentence.
So skip the "need" for sex with this lady, for it is obvious that she does not have a sensitivity for YOUR feelings, but is only interested in fulfilling HER neurotic needs, whatever they are.
Leave that woman, break the p 0 r n habit no matter how much effort it takes, and learn about real mature (at any age) women and the utterly fantastic life you can have with the right "friend". The sex that follows will be so powerful that you will be glad you stopped chasing a lie, and brought your mind back from it's captivity.