Yeah but the rockiness was only because they were putting their career pursuits over their relationship. We live in a world where we're taught from a young age that fulfilment comes from our career ambitions and so everything should be sacrificed on the altar of ambition. If someone's 'holding you back' cut them out of your life and be the best you you can be! I think the film does a good job at shining a light on that view of the world and asking whether it's worth it.
Like I said, I think it's a valid read of the film in light of what Chazelle did with First Man, which is portraying what is essentially the peak of human achievement to that point, landing a man on the moon, and the way Armstrong sacrifices his family life in pursuit of that goal and (in the film at least, no idea about the actual real life Armstrong) he's unfulfilled.
