The title already spoils it but, unbeknownst to the husband, the pizza delivery boy turns out to be Sana's nephew as revealed on the last scene when the couple meet him by chance.
Included both a low resolution version and a HD one, which the later being the one available here.
@MacacoLendario Probably will do it at some point in the future. I must admit that due to personal preferences I would have preferred the author to focus on adult partners like in the first one, but I like her character design and the fact that compared to other 3d artists he's really trying to put an story there.