one of the girls will get impregnated but not by the MC, it will be another male teacher which afterwards will piss out, deny it or some other shit like that. MC will feel bad about it, even responsible for not noticing and married the student to prevent her from getting shunned as an slut or something like that. And the culprit is the ugly bastard teacher which got introduced on the first chapter.
still its kind of fucked up if you consider he basicly commited social sucide with that move, furthermore looking at the combination of tags this series has, he probably is going to end up a social outcast any way.
Instead of the usual 14 year old virgin MC that has never seen boobs in his whole life, an actual adult one that's hard to crack in the same situation would have been more interesting.