Let me just say, anyone who thinks the dialog was dragged out, think of how Jake's victims felt in the car with him. There are many times in the film where they hint that he is a person with failed dreams, who despised any woman who had higher asperasions or were more talented than he was. He would talk and talk for hours and you could see the frustration in her face over time.
This was MY understanding of the movie: He did this often, would bring woman back home to meet his parents, and then would let them freeze to death eventually. When they first arrive to his home, he shows the main protaganist his barn, and in the barn you see two frozen lambs, but the sheep are still perfectly fine, he becomes uneasy and uncomfortable when she asks him why and how the lambs died. The pig he talks about died by getting eaten by maggots, hinting that there is mosty likely rotting flesh underneath. He had an obsession with freezing people, woman to be exact. And maybe the reason his parents change in age so frequently is because he would bring woman over throughout his life. The reason it's so surreal and drawn out, almost as if details change, (the main character's name changes frequently throughout the movie), is because we are watching the movie through Jake's eyes as an older man (the janitor) He has dementia, just like his father did. So details change, names change, and things don't always make sense. When we hear her thoughts, like when she says "I'm thinking of ending things" That is not us being able to read her mind, it is Jake's idea of what he thinks she is thinking about him, which is why it almost appears as though he can hear her thoughts. He wanted so badly to be accepted, and seen as a talented genius, but failed so many times, he was scared of rejection so much that he would put ideas in his head, eventually leading him to kill his victims. He was recognized by the ladies in the ice cream shop, because he had been there before, trying the same tactic of buying ice cream, not eating it, and then finding an excuse to "throw it out" so he could leave her in the car to freeze to death. I think the movie was brilliant, almost like a puzzle that you have to put together yourself. The movie doesn't feed you all of the answers on a silver spoon, it makes you dig a little deeper and come to a conclusion yourself. The very end of the movie, where he's on a stage in front of a crowd of people that he knows and loves, is a representation of what he wishes his life could have been, everyone he knows cheering for him. He never got that, he's a janitor at a high school, the furthest thing from a successful artist.