I think I've discovered the solution to my issue: it's bizarre and incomprehensible, and I present it here only for analysis by larger brains.
I saw somewhere that IRS (even IRS for mild romance scenes) is incompatible with the newest version of mild romances. So I uninstalled mild romance scenes, plugged in IRS standalone, reloaded a pre-Landsmeet save, ran through it, and voila - the "still in love" flag sets, I can get all the way through that fourth "Are you going to be all right?" option post-breakup, everyone is deliciously miserable, etc etc. However, continuing this game, Morrigan never mentions Alistair losing the woman he loves during her ritual offer, and when I get to Denerim for the final battle, none of the romance dialog appears for Alistair's goodbye.
The only thing I had that did anything to Morrigan was the Morrigan Dialog Restoration patch, so I removed it from my override folder and tried again from pre-Landsmeet. Sure enough, Morrigan now referenced Alistair losing the woman he loved and I got my sad goodbyes at the Denerim gates (no kiss, though, but whatever I got most of what I wanted).
I've heard of IRS and the Morrigan Restoration Patch coming into conflict when there was a alistair_main.dlg file in MRP, but I have no idea why the two would fight when there's nothing they both share.
Thank you for the assistance - if anyone knows why any of this happened, or where/when the plot flag stuff cheesed up, I'd be interested in knowing the science behind the Saddest Ending Ever Failure.
A STUPID EDIT: I've just realized I also have Gatekisses on here - when Gatekisses is removed, my Denerim goodbye dialog reverts to friend, so I officially have absolutely no idea what's going on here.
Modifié par CueEllTee, 11 novembre 2013 - 04:33 .