thanks! to nit-pick some more :P
after Serene fires the MC it is still possible to work at the shop and walking her home.
iirc this event is serevents 5, this could be used to block the activities ("and not serevents == 5")
to end this on a more positive note: I only critisize to make a game I like even better :D
edit: thinking about it a little bit more it is probably serevents 6. and I should work, and not thinking about renpy code ;)