I still think she was groomed by this man and went voluntarily with him. She was a shy girl from a farm and now living and working in simple jobs in Kansas. Maybe he pretended to be a photographer, movie or show producer and take her to Las Vegas and make her famous. Of course since her family would not like it, she would have to be quiet to them about it all.. Or maybe he confessed his "love" and said he would marry her and give her a beautiful life.
He may have done the same to other young women in the past (not necessarily killing them but leaving them after a while after using them). Jolaine was vulnerable. Shy, quiet, very young and probably a little bit unhappy in her diner job. And she knew she was good looking. Ideal candidate for a predator.
Everything went according to plan until she had the accident. Apparently he did not even know she was dead as he continued to send postcards in her name the following weeks. He did not want to take responsibility and also he lied about their relationship, lied about their name and was with a girl below the age of consent.