First of all, there's no romance between Vincent and Rona, nor does Vincent get with anyone until the most recent WN chapter. However, even with that I have my qualms: the buildup is shaky, if not non-existent, and so sudden. I kid you not, it went like, "Vincent, will you marry me?" (Rin), "Ok." (Vincent). Furthermore, the comedy act must be camouflaged really well, because I've seen (non-comedy) horror stories more comedic than this.
To summarize, this is a slice-of-life story, whereby Vincent's eyes, the reader will experience what it's like to be a side character despite being the "protagonist." It's that dull.