Seems like people are lost on this page chapter.
The title is "first love", the POV is from the guy, the girl is his first love, they got together and are going to have sex, but she declares she hates condoms, meaning she already had experiences, for a virgin that is a big smack, it means the pure-looking girl that is his first love already had sexual experiences, and enough to say with calm that she wants to go raw, for westerners that isn't a super big deal, for the stereotype JP protagonist is, see how his hand is trembling.
Another note, seems like some people think is always the same guy POV, is not, most likely every single one have a different guy, as the thieving cat always uses the GF of the guy having smaller breasts is very unlikely it can be him everytime...but it could be B-cup, poor girl.