There's no reason to get ahead of ourselves on the possibility of romance--the story isn't.
When a good writer seems to have things well in hand, I'm inclined to just let it roll without putting too many expectations on the ultimate outcome.
Appealing characters, grown-up writing, attention to detail, nice pacing on the episodes--steady as she goes, as far as I'm concerned.
I personally wasn't actually putting expectations for the outcome. Rather, when this series started, I wanted to see these two fall for each other in the end, with Midori getting over her old love, so that she doesn't see Haru as Tsumugi. But now, I wish to see these two to grow as a family, and if the series keeps going the same way as it has, my initial desire to see them as a couple in the end will probably disappear and I'll probably end up disliking if that's how the series will end.
For now though, I wouldn't in any way mind them falling for each other.