As a Westerner, it's hard for me to know whether the original tone in Korean was harsh or just unusually direct. The way it is presented here in English is great. Yes, it sucks to be rejected, but I appreciate the unequivocal language which means that any misunderstanding is willful and undeserving of extended sympathy. And other than the reference to his young physical losses to Leah (which she already told us was a huge turnoff for her), Leah wasn't presented as being contemptuous in her refusal.
There's really no acceptable way to turn a guy down in the US. If the woman is gentle the man won't stop trying because "she's playing hard to get" and if the woman is firm she's heartless. I can't speak for other English-speaking countries, but in the US it's a very difficult line to walk. Kudos to the translator, as well as the writer, for the portrayal here. I'm bumping up my rating.