I think the concept of growing up is reasonable and I think Haruto needed to grow up before being able to raise a family, but ya, all the dramatic fireworks necessary to make it happen have been a bit much. Adachi was a good teacher though. Like Asuka, she was someone to get him ready for the next step. Asuka healed his heart while Adachi strengthened his spirit. These are decent life lessons. The execution of the past arc was rather abrupt and unrefined though.
If it does end with Yuzuki hiding her pregnancy, well, that's par for the course but kind of crappy (especially since it means that friends and family will have to have also agreed not to tell him, there is no way that Yuzuki could have avoided bumping into a mutual friend with large belly and then a baby). I consider Yuzuki an essential part of the franchise--I mean she's the whole premise really, the outsider girl who disrupts Haruto's easygoing life and changes him. So if he doesn't actually end up in a permanent relationship with her, one will wonder what the heck the last 250 chapters were for...