I enjoy having relations with very old women. Is this normal for a healthy young male?

I am 38, tall, athletic, with a very vigorous drive and well endowed. But I am presently dating a 58 year old woman. I find I cannot get ually attracted to any women of less than 50 years old. I like the conversation, the lack of any sort of headtrips, and the frank enjoyment of without strings these women bring to the bed. But I have recently gone beyond what is decent and sane by sleeping with a 91 year old woman. He body was sensational and equal to that of a woman in her 30's and it was a headrush for me to roll in the sheets with a woman who was already romping around when talking movies were just starting Her old body fascinates me and her mind captivates me. I find these women far more attractive than my wife who is in her twenties. How far can this obsession go?