I have had a similar problem in my dating life. It may be unrealistic to look soley for a woman with super long hair, however if you find the right woman that you like and makes you happy, then go with her. I'm married to a woman who had hair to her chest when i met her and she makes me very happy when Im around her and I told her about my love and fetish for long hair and chances are she will want to grow it out to make you happy. We have been together for 6 years and now her hair is to the top of her thighs. I brush it for her every night and she has promised me she will let it grow down to her knees, if not longer.

So whilst dating, I would give up the expectation and find someone and if they are right they will grow their hair for you but just be patient with them.