first of all, he is not your ordinary beta MC, cause in earlier chapter He want to fuck dem girl on first day.
Secondly he only doesnt fuck em cause he doesn't know condom magic, and yeah it exist on this world..
thirdly the mc just need prepared, if he make girl pregnant at least he has money and people who can take care of them when he leaving.
and lastly the author is a dick for not making him knowing the condom magic and blue balled the MC