I give a good look at code of the game...
The condition for the night event "wait for something to happen at night" is
if Mprog == 26 and M_story == 2 and M_lust == 3:
jump M29s2
Alas you have to be on Molly path (M_story == 2) and Molly lust is 3.
Now, Molly build lust every day:
if Mprog >= 26 and M_lust <= 3:
$ M_lust += 1
So, after the date reward scene, you have to skip 3 days.
After this I found an interesting, 100% avoidable, bug.
Make Lilly wear the buttplug in the morning, make it impossible to trigger the fist date event with Molly when you came back home from uni. Be aware