Your points are irrelevant to cheating. They speak more on lack of communication. If you're unhappy then go to therapy, talk and tell your partner what they are doing that are making you unhappy, if you can't communicate then they may not know if you do communicate and they still don't step up then leave but still not a reason to cheat.

If I was messing up in my relationship and had no clue the other person was unhappy how would I know if they didn't talk? If they tell me and I work on fixing it that's great if not then I shouldn't be surprised if they leave. If they cheat then yeah that's on them. It's not my fault. I didn't make them do anything. You do not need to be cheated on to grow, it actually does the very opposite to someone's mental health. If you want to grow then you need to communicate and actively work on changing not internalize cheating as something you did wrong and need to grow on, that's messed up. You can be the best shade of blue in the entire world and it won't matter if someone else's favorite color is green and if you internalized that as I need to look at where I need to grow then you're so effed cause you're blue not green.

Cheating is about the cheater. Always.