Julia and Joel: It's probably been said before, but I always interpreted the situation leading to the marriage breakdown as Julia being clearly depressed. Adoption related depression/anxiety/stress, closely followed by a loss of self esteem when she was no longer working. I think this is what she was referencing when she said she needed Joel and he was weak.
But I think that short scene with Julia and Camille was the writers short handed way of trying to explain what Joel may have been feeling. Julia saw him as being 'weak' through all those difficult stages, when maybe he was feeling just as vulnerable as she was, and he needed her support. Or maybe he was misinterpreting her poor behaviour as selfishness, and not symptoms of depression.
Why Joel didn't articulate any of that, though, is beyond me. Lazy writing, I guess. But I see no fault in Camille and Zeke encouraging their daughter to give the marriage another go, especially as there is no doubt that they both still love each other.
Max/Kristina/Adam: We are definitely being punked by the writers. That is all.