I understand what you mean.
I think this open ending is justified, it leaves so many possibilities for imagination to run wild, but at the same time it is closed enough to have a solid answer. I mean if it ended where they got married and had a kid that wouldn't fit the current story image (mind you I'm rutting for this couple) it would just feel off, I mean happily ever after isn't bad but not everything is perfect and this story shows that I think it depicts real life, we may remember yesterday, and we have today, but we still have tomorrow. though I don't know if I'd enjoy a sequel, depends on the story.
im kind of not satisfied with that ending. the story is a little silly but cute. it has so much potential