i have the the darkest day mod installed and i was wondering, does the game end when you beat irencius the last time, or can you still go around and finish some quest, also does anybody know if when you play the tdd part does all the romance end? cuz i was almost to dating jahieria but didnt have enough time to finish before i killed irenecius

Yes it does, when Irenicus dies in Hell it's all over. So you can't do quests or finish romances. Althought you can continue romances in ToB.

I thought that with TDD, you get the major mod quest after you beat Irenicus in Hell. Not sure about this though.

You're supposed to be able to talk to Elliseme after waking up from Hell and get a quest. I couldn't do it because I have ToB.