Elvenking - Romance and Wrath
Half of GNR's discography
Luca Turilli - Demonheart - seems to be about some dude who finds out his girl is a demon, so he has to dump her, in truly epic fashion
Queensryche - Operation Mindcrime has something like that...
Also, Kamelot has a ton, if you like power metal. Try their most recent album, Ghost Opera. Also, their two albums before that (Epica and The Black Halo) also have some songs like that. A few songs of theirs with this kind of theme:
-Ghost Opera
-Love You To Death
-Eden Echo
-Temples of Gold
-On The Coldest Winter Night
-The Haunting (Somewhere in Time)
-Abandoned
-The Sailorman's Hymn
Those are some I can think of right now. They really have a bunch.
I second Etos, though I also would recommend listening to their best albums like 'A Virgin and a Whore' and 'Chaotic Beauty', 'Before the Bleeding Sun' is also amazing.
Though imo, I think Draconian is totally what you're looking for. Listen to 'Arcane Rain Fell' or 'The Burning Halo' very hard hitting and emotive but not over-heavy ( well, since its doom/gothic ) You should probably also give Theatre Of Tragedy's first two albums though, in the same vein.
I was just kidding btw...
Try A Life Once Lost, they're more of a fuck you to a lost relationship, but they pretty damn good. Groove metal style music.