i think you lot are overestimating how small the town is. didn't the manga start by saying it was a small town of "just 30 000 people"?
I am simplifying not overestimating how small. Farming towns tend to be much older populations in general. Most of the young men move to the cities to find work, young women tend to as well but don't tend to do so as quickly. This results in there being a skewed gender ratio for that age range. Yes he isn't the only man his age, but there is a shortage of men of his age that the women can chose from, add in that he is one of very few who is stable and for sure not going to move away, he would be a top pick for any girl who doesn't want to move from her hometown.
30,000 may seem like a lot, but for instance the US census bureau defines a small town as a population between 25,000 and 50,000. There are a lot of ratios that bring that bring down what percent of that number are young folk. Farm towns have pretty much a population cap as there is only so much land available to farm, as well as only so much demand for produce. Look up average farmer ages, you'll find answers like only 11% are 20-30 and a whopping 67% is over 40. This leaves very little job options for kids other than moving away. So yeah he is one of very few options available.