Benefit to only dating one person?

[1Erik1]

Well I wanted to have my first playthrough be true to the original and date everyone, but considering I have a choice now to decline I was wondering if there is a benefit, apart from being able to avoid reverse arcana, to only dating one person.

Like are there new events that won't happen if I date multiple people/only happen if I reject all but one?

Because at the culture festival I did seem to have a scene that suggested how I am dating multiple people, however I didn't have a single romance at that point. So if I get those scenes no matter what/where the game assumes I am in a harem route anyways, I thought what's the point in declining romances then?