I don't think the end was a true end. I think the manga must have gotten popular after the end and it was restarted where it left off. It was around a holiday and Zen's relatives were pressuring his dad to get married. There was some event at a shrine where he made some progress, although he did not know it at the time. I am so glad it kept going. If there are 6 more volumes I hope they start dating way before the end.