OK. I may be projecting, but I'm look at this from the other side of a different perspective perhaps.
The 1st 2 years of any relationship are much like any other. Between 18m and 2 years however some relationships start to show signs that were not there before.
The unexpected reaction, when you expect your DP to react in a certain way and he doesn't, not quite. Not enough for you to have a discussion about, but something to surprise you, and not in a nice way, in a slightly disappointing way.
When you identify something that bothers you, you communicate this to him, but he doesn't seem to take in on board. Ever.
Why does he browse MN? Did he do this before you were with him? I'm assuming he knows you post here?
You felt a lightning bolt when you met him right? Amazing sex? he was full on in persuing you, made you feel like the only woman alive on earth?
You love him, completely, mad about him, he is The One.... BUT somehow you feel that YOU are not the ONE for him??
So are you going to try to BE the person that would be The One for him?
That's the next step in this process, that you change, modify yourself, take it on board that him making insensitive comments/reactions to things he KNOWS DAMNED WELL hurt you, is 'Just Him'
You're being taught to normalise.
The relationship you describe is showing signs of him being abusive. If a normal person knows that to say X upsets you, they make damned sure that they never EVER say that again. You said yourself that you'd learn the first time. He is NOT. He's upset you 5 times on this subject already, you tell him it breaks your heart, but he still does it.
This guy will keep doing this. He is not The One. The One will NOT knowingly hurt you repeatedly. He will do everything he can to support you, to make you feel better, stronger, happier. This guy you have will destroy you eventually. In any way he can. Trust me.
The relationship I describe is the same relationship I was been in for the last 11 years. In the end I barely left the house, was a psychological shadow of my former self. I've attended group therapy, individual therapy, and the Freedom Programme. It's been exhausting and the journey is far from over yet. I may never fully recover.
I'm embarking on a new relationship myself, it's hard going, but if I saw the above happening in my relationship I'd walk without a second thought. I'm not getting trapped in that hell again.