I'm wondering if there's any indication from the creator that pregnancy will eventually extend to the lovely Irina?
It seems plausible that I'm not the only one who finds no added appeal in "landladies" and "roommates"* (quite the opposite, really) but who is depraved enough to find excitement in the notion of otherwise wholesome sex being corrupted into something as profane as breeding.
If I could be bothered, I would launch a campaign for equal opportunities for love interests who are, by accident of birth and no fault of their own, tragically not immediate blood relatives of the MC.
*Except in the very rare instances where characters are actually conventional landladies or roommates and these aren't just very awkwardly applied euphemisms. My New Roommate for example, despite its misleading title, is a highly original erotic game that casts off the shackles of ubiquitous tropes and explores a whole new world of sexual tensions that arise between persons who initially cohabit for the novel purpose of dividing the financial burden of rent and not, as one would normally expect, because they have the same parents. Of course, such experimentation is unlikely to be widely appreciated in its time.