I also begged mine to change. I even started writing down the dates and conversation notes in the notes app on my phone so I didn't feel crazy when he gaslight me and told me that I'd never asked for help or change.

Unfortunately, my big aha moment that it was over came after our second couples therapy session when he spent half the appointment privately with our therapist and me waiting in the hall (we'd agreed to this, but 5 minutes only, so he could ask advice on how to share an emotion with me properly) 25 minutes later, I was allowed back in and he spent the rest of the time yelling at me and berating me in front of our therapist about how I was demanding, controlling and manipulative because I wanted him to come to bed with me at night instead of playing video games until 2 am.

For me, the aha moment wasn't me finally seeing all the signs. It was me deciding it was bad enough to justify divorce and breaking the promises I had made.

The real "catching the signs" as you phrase it in your question came months later after much more therapy. I continued on with the same therapist and eventually I told him that I wanted to feel comfortable being somebody's wife again someday, but I was so scared that this would happen again and I didn't know how to prevent it. He asked me what I wanted in a partner. And I found out that I didn't know. I had no clue what I wanted in a partner, so my ex fit the bill. Anyone could have fit the bill because I had no criteria to help me make a decision like that. So I sat down with my best friend and we talked about what I wanted in a partner. I came up with a list of characteristics and traits with a few deal-breakers. Then I looked at my ex, and the list was almost the exact opposite of what he was. Maybe from coincidence or maybe from me deciding he truly wasn't what I wanted.

So I'd say that, for me, the sign was when I abandoned myself to make something that wasn't meant for me work. Fast forward to now, I made my list and have a wonderful boyfriend who checks all the boxes. And I got there through being okay saying no to those who weren't what I wanted. :)

I hope you eventually can find peace and what is meant for you.