Should I mention the manga "We never learn?" There the mangaka chose the least likely girl for the ending, disappointing many readers. Surprising everyone again, he then did two more endings for the most likely girls, finishing with two more endings for the two women in-between. I found the multiple endings fulfilling in themselves, if I never saw the rest of them, but found the concept as a whole to be cheap. He should have just chosen one and gone with it. I didn't think the first ending was bad...

I don't know if they confirmed his father was a monk or simply he was a monk in training, if it's the first then it allows him to marry but not necessarily date because... arranged marriage dating isn't necessary (usually a meeting or multiple meetings but usually not a date).

Most harems have 4-5 girls, so far we have a confirmed 3 (I'd like to see far less Mona and more of these other two), and potential fourth with the new school year kouhai. That leaves the angle you mentioned and why I think he confirmed on his inner dialog that that he'd turn her down if it was a date, I believe they will eventually, unfortunately to drag it out, his... drum roll... arranged marriage partner later on.