I guess really we can't use DA2 as an accurate representation of romance arcs/story arcs for DAI because the game had such a short development time that a lot of things were cut and everything was condensed, not to mention it was a lot shorter in length than DA:O.
I actually had real problems with how DA2 handled the romances. The sex was mandatory and that made me very uncomfortable. (Although, with Anders, we never see them "naked" and they're both dressed right after, so I headcanon with my canon Hawke that nothing more than necking happened.
) Heck, in DAO, you could go the entire game in a romance with Zevran and never have sex with him. Zevran. And the game even acknowledged it! In DA2, it felt more like I was just picking the person I wanted, and the romance was like a small movie I, the player, had no part in. It was very impersonal.
So my hopes for DAI romances are that they are definitely more, ah, gated than DAO's, drawing out the experiences by using the main plot as triggering points for the next step, but have far more options within the romance than DA2.
For a Cullen romance, because of GE's tweets on the subject, I assume there will be stuttering in the early parts of the romance. And a bit of awkwardness. In my mind, I see Cullen being the kind of person to bump into a table as he's nervously chattering at the Inquisitor. But as others have said, he'll grow more comfortable with the situation and that'll stop. Which is good. Even though the stuttering is what endeared me to Cullen, I'm not sure I could handle an entire romance where he was staring at his feet, or jumping like a spooked horse whenever my Inquisitor made a move on him. 
What I wonder, is if picking one type of advisor's suggestions over the others and having the majority of your captured keeps decorated in that advisor's style will have a drastic effect on the fate of Thedas?
For example, let's say I ran with every suggestion Cullen put forward and made all my keeps militaristic because I didn't want to miss any dialogue or interaction with him, would I end up with Ferelden/Orlais looking like battlefield and "peace" being formed via a strict army style Inquisition?
Could it be that going all/mostly militant/espionage/political could actually have a negative effect? And striking a balance where each facet is used within it's optimal situation/environment is what would be considered the "best" way to go about things? We really need to know more on how this advisor thing will work, lol.
I don't think that this is how they will be gating the advisors on a personal level. I mean, perhaps the more military keeps you have the more military troops you have, meaning your army is stronger. Cullen, himself, would be unaffected in your interactions for the most part. Or, at least, it wouldn't be every keep. Perhaps a few to really open up Cullen entirely. I'd be very disappointed if a sneaky character who saw less value in outright confrontation was locked out of dialogue with Cullen because more of their keeps were espionage-focused.
That said, I'd bet that some quests will open or close depending on the balance of your keeps. Perhaps having a lot of military keeps will make the populace view you as a warlord, or a lot of espionage keeps will make you almost unknown to them, or a lot of commerce keeps will make you unpopular with the poor.
Also: 100 pages to go! Any guesstimates on when we'll reach that grand ol' page 1000?