But just in three days how do I get them pregnant, also whenever I go back to the reunion all the corruption points and love points are back to zero, but some of the events require "love 6" or "corruption 5".
Corruption is in levels, after a set of events for each character they can progress to the next level, which you can then unlock in the end of run menu for each character.
At higher corruption levels they will becomes significantly more sexual and there will be plenty of opportunities to get them pregnant. Given how the past changes from these, eventually they will arrive at the reunion pregnant.