Well obviously it is not just about a glass. It's about being an adult, and doing things as a team.
There will have been countless versions of the glass incident where the bloke just thought 'I don't have to make an effort for my wife' and the glass will be the tip of the iceberg. There will have been shoes in front of doors, bread he couldn't be bothered to get out of the freezer, empty packets put back in the fridge, skid marks in the toilet, full hoover bags, empty petrol tanks in the car, run down batteries, procrastinated repairs, damaged domestic items, lost passports and forgotten errands or messages. In. Their. Hundreds.
Meanwhile the wife will have been circling around endlessly trying to smooth over various minor domestic hiccups and wrinkles practically on an hourly basis, probably while holding down a job and looking after kids, and one day she will have asked herself "Do I really need this man child in my life?' Meanwhile her husband was apparently oblivious to the fact she was taking so much responsibility for everything minor, trivial and everyday in his life. Because otherwise, frankly, either or both of them would go under.
Any one of the minor infractions sounds ridiculous on their own. A glass on the side (even I do that, frankly)? A messy toilet? Forgetting to defrost something? Never changing the hoover bag? Letting the petrol run down? Grounds for divorce??? Only for a mad person. But what this man has recognised in the blog post is that it is not about that. Before he saw the light, he expected his wife to be the grown up at all times and plug all the holes in their domestic life. Then the day came when he had effectively worn her out. By the time he recognised this, it was too late and she had moved on emotionally.
Moral of the story is if you want a relationship to work, don't treat the other person like a household appliance, your mother/father, or a member of your domestic staff.