I'm not sure if anyone else has thought about this, but what if one of the two race gated LIs is actually Cullen? And that he couldn't be romanced by human Inquisitor because they are related by blood in some way?
The thought occurred to me since David Gaider once said very teasingly something along the lines "So that's Cullen's full/last name". To me it sounds like there was something surprising in his last name - and that it was important enough to be tweeted about. At first I thought that he might be King Maric and Fiona's son but yesterday it was confirmed that Alistair is their son so that trashed it.
Another reason why I considered this was because yesterday in the Q/A one of the developers said that two of the romances would be race restricted because of "story reasons" - not personal race preference reasons. The devs might just have said story reasons just because no better wording occurred to them atm but yeah.
I know this doesn't sound very solid speculation but wanted to say it anyway.