I am not sure. He usually makes stupid decisions, is impulsive when he should think first, indecisive when she should act. He is understanding only when it suits him, which reeks of insincerity. He has no plan. I dislike his face, his way of speaking. There are really very few scenes in which I do like him.
It sounds to me more like you just don't like him on a visceral level, and it's coloring your perception of anything he does rather than maintaining some objectivity about the character. Seriously.
He is 40 years old at the end. As an adolescent, it appears, he was the leaping-in kind of guy. He stills leaps in often. When he does not, it is because he struggles with what I jokingly dubbed his ESFJ complex, the question of what he should do as Nate, the oldest child, the father, the husband, as opposed to what he feels like doing. I am willing to concede he might be an extroverted ISFP, but he certainly feels like an extrovert to me.
At best, it would be one of the low-key extroverts... I don't think ESFP falls into that category.
Much of the time you are also seeing him engaging people he is familiar with. With people he is not familiar with, they are receiving a packaged image of Nate especially in his role as the "nice gracious funeral director" that always has to do and say the right thing in order to be the "nicest, warmest, most understanding person in the world."
But there are typically two selves -- his public face, and then the one he shows in private to his family. He is far more personal and engaged with his family, and he throws his weight around more there, and even treats himself as the pseudo-father figure, which his two siblings sometimes give him crap for. Extroverts by nature typically are themselves in the external face; the difficulty comes in cultivating an internal self, that's the one they typically have to work at and bring into sync.
But, Jennifer, please feel free to grace this thread with your superior reading.
Already did.
But thanks for graciously offering me your permission.
I guess it's his very ineptitude that I find so sympathetic, because it's in tragic contrast to his earnestness. He so wants to be doing it right, and so has no clue what that could mean for him. I'm afraid I relate all too well. It also seems to me that life plays shitty tricks on him. The hot beautiful woman turns out to one of the hardest possible people to live with; the granola girlfriend he left behind turns out to carry incredible obligations; the gift of an inheritance imposes crushing responsibilities -- he never gets a free lunch. And just about the time he adjusts with his best available grace to what fate has thrown his way, she turns around and takes it back, or throws another monkey wrench in the works.
That's more of how I see him.
He's an idealist who had a lot of ideas about how life should have fit together; he had wonderful intentions, but nothing ever seems to pan out as he thought; he's got an unstable mother so he feels like he has to be in charge of the family; yet he can't be the perfect "golden child" oldest figure in the family anymore. Don't forget that Lisa was murdered, his one chance at a "normal" existence taken from him, which left him back with Brenda (where he was basically cheating with her on her boyfriend because at the time she's pretty messed up too).
You basically see him start to revise his idealism, because it's not making him happy and in fact is creating a lot of pain for him; and instead he takes a tougher, more self-absorbed, grittier approach to life. I think it's the right overall path for him but only a way stage, and it's typical for introverted idealists. Another reason for him to be an introvert -- the idealism was him positioning himself consciously against the world a certain way (rather than identifying with the world), and he's constantly speculating on that border between him and external life. It's a typical division between self and world in introverts, and how we express and experience power.
As I've said, I did not like him very much by the end, but I did see how he got to where he got and why, and I could track his logic. In some ways, I feel like Brenda was coming out of her mess stronger, though.