So the disconnect was so unbelievable to me, bc even a disconnected Hannah and Adam felt more meaningful than any scene I have seen with Jessa and Adam.

I really agree with this. When they were planning to move in together and Hannah started to cry with the realization that this was a fantasy they couldn't live out, I really didn't understand what was so far-fetched about their plans that made her come to this realization. The only "red-flag" moment for me was when Adam and Hannah were shopping for baby things, and Adam said something like "it will be so great to get my mind focused on something for a while" or something like that... it implied that Adam hasn't really understood the severity of parenting as a lifelong commitment and not just a temporary project to occupy himself with. BUT that could have been a conversation they had, Hannah questioning if he was REALLY committed to this instead of just instantly realizing it wouldn't work out. I don't know. It was kind of beautiful that they know each other so well to both realize at the same time it won't work, without any words, but the romantic in me still clings to the ending where they stay together and love conquers all.