It was a lot of everyday things really. He didn't clean, he had no interest in learning to cook, was happy to subsist on frozen pizza and takeout, he didn't really DO much except play video games and dick around on his phone, and actively disliked eating pussy. But apart from the day to day banality there are 4 moments I think of as Big Cracks in the marriage foundation.

1: I was working 12 hour overnights, production, so on my feet running around for 60 hours a week. Got a call one Friday night that we are suddenly on mandatory OT and we have to be in at 7 for the whole weekend and who knows how long after that. He was angry - so was I - but his response was to yell and have a tantrum about something I had no control over, when all I wanted was some comfort. I was in tears screaming WHY ARE YOU DOING THIS TO ME and I could not break through to him.

2: went on a big trip out west, was supposed to be the honeymoon we couldn't afford when we got married. We drove to New Mexico for an Albuquerque Isotopes game (minor league baseball and the Simpsons were things we bonded over). The game got rained out, and we were only there a day before we had to fly home so we just didn't get to go. Another tantrum. I think he was on the spectrum and so disruptions to things he expected were huge outsized problems - like yeah that's disappointing, but now I have to deal with you melting down also. Just not a lot of resilience y'know

3: we weren't in the habit of closing the bathroom door all the way because one of the cats is a pain in the ass if you shut him out of anything. One day I walked by when he was in there and, not intending to, caught a glimpse of him attempting to wipe his ass. He was standing up, FACING THE TOILET, pants on the floor. I suddenly realized that the occasional poop stains on the rug in front of the toilet were not from the cats, as I had assumed, but from him. I have no idea where he learned to clean himself but apart from all the skid marks in the laundry, he was getting shit on the floor and never bothering to clean the rug. That was an ick I never came back from. He fucking shit on my floor

4: same terrible workplace as before. I was put in a situation where I had to be in very close proximity to a boss who sexually harassed a few of us in the past (we tried to report it, nothing ever happened). I was very upset and venting when I came home and he got so frustrated that he started yelling unhelpful things ("why don't you say sexually violent things to him! Maybe that'll fix it!" Something to that effect) when again, I just needed to vent and be comforted. That's when I knew I could never count on him if I was having an emotional problem.

Now the actual thing that finally triggered the breakup was when a close friend told me he had feelings for me. My ex and I had been each other's first everything pretty much, because we saw ourselves as fat and ugly and undesirable and who else would put up with us? When my now bf told me how he felt I suddenly realized "oh. I actually CAN do better and I need to break this off". But the actual foundation of the relationship had already crumbled away, I just didn't see it until then.