No, this is not a sudden character change, or flashback. This is just Oleg's fantasy. And he has such fantasies about Serin, Kilaya, Irina and even Alice (the latter with shame).
Don't forget that you can offer your ideas about comics in the comments (sex postures, types of sex, details, and so on (except fertilization)). The best ideas will be used in the comic, and their authors will be referred to in the comic as "Co-authors".