I'd say it does have to do with the expectations that surround men as being the 'head of the house', especially in a country like Japan. He loves Yuzuki, and it was obvious that both were starting to think about reaching 'the next level'. Actually starting a family, getting married and all that. However, Haruto probably felt pressured into finding "a real" job as opposed to what he had, and he probably feels, especially considering his line about his pride as a man, that doing this was the easiest way to support Yuzuki and their dreams together. Also, let's not forget that he had just witnessed his best male friend become a father, as well as hitting it off into a presumably good enough job, so surely all that ends up taking a toll on him when deciding about moving to Kochi and leaving Yuzuki.
Anyway, I was expecting pregnant Yuzuki, but this setup was also very interesting. Things seemed to be going well before, so I guess I didn't think much about it, but Yuzuki's worried "What should I do?" line definitely made me think about the real situation they're in. Regarding Yuzuki herself, she obviously misses Haruto way too much, and has been making some absurd efforts to be together with him. I appreciate that in her, and I understand that it must be quite hard to be separated after spending a whole year under the same roof. However, and this is totally in-character for Yuzuki who has always been a little pushy (reason why I like her), she's unconsciously putting more and more pressure on Haruto. I mean, if you think about it, if it wasn't for Yuzuki's efforts, there is no guarantee that Haruto would ever have found the time to go see her, which would probably have meant that both of them would not have met for a considerable amount of time.
On the other hand, it's tough because I can't just fault Haruto, either. Corporate world is what it is, and he's just playing by the rules in order to keep his job, a job he got while probably thinking of what would be best for him AND Yuzuki. In this chapter, once again, we had him putting his work ahead of her, and I guess Seo's just slowly building up to a point where Haruto will have to make a choice. Here, again, I think he's definitely making a good job at showing that, under normal circumstances, Haruto will obviously let go of his work to keep Yuzuki. He doesn't seem to particularly love it or anything, and I guess that's where Adachi's character comes into the play. He's been looking at her as a role model of sorts, but it seems he still hasn't realized that they're different in that she truly loves what she does, whereas I don't feel any 'passion' for it from him.
Anyway, it was a painful read because I could see how both were full of doubts and hurting, which isn't something I appreciate 'cause I took a real liking to these two characters as a couple. On the other hand, though, I'd say Seo is definitely doing some good writing here and, if all goes as planned, we could see Haruto once again maturing quite a bit from this experience. He's turned down a job before out of pride that I still can't quite get over it, and the comment about how he "sucked at life" stuck with me to this day. But maybe all of this needed to happen for him to clear up some misconceptions about how things work out there.