Maybe imagine it long or watch some content online before you have sex.

My wife went from thick one length just past mid back to a layered bob and then a perm. Wasnt a huge fan but it didnt take long for it to get to shoulders again and be able to put it up/grab/hairjob. I used to imagine it long or id watch stuff online before getting kinky. Few years on and she hasnt let it get longer than shoulders but im fine with it and i can get a hard on just from her.