Age gaps in relationships ... not uncommon I reckon. And just one of the many themes this movie takes under a microscope. Sometimes things happen and if you can't or won't talk about them, there is a fair chance of you going insane. Certain fruits or other things may help you get the taste of insanity too.
But it is not just that age gap, a previous relationship or a step daughter. Though the last part may very well be a large part of our main character losing her marbles as they say. I don't want to boil it down to "woman wants her own kid", because that is also not just it (if it even is something you can see in here).
So as you can see the movie might be way more complex in its themes and what it sets out to do. As many would argue though it is flawed and it does not always achieve or convey any of those themes to the viewer in a proper manner. You have to have love for the independent movie - the low budget kind that is very weird too. Because this is what you get here. Not great, bur far from bad too. An interesting dive into human psyche with quite the appalling ending (in a good or bad way you ask? Well I can't really answer that a certain way - because bad might be good or at least interesting even if devastating ... while good might be bad and pulling punches ...)