Considering I haven't finished the entire game yet, take my comments with a grain of salt.
Bioware's games have nearly always had a large portion of their content devoted to the companions. More recently, especially since Mass Effect, more of that companion content has gravitated towards romantic storylines. However, from everything that I remember from Knights of the Old Republic, the Mass Effect series, and the Dragon Age series before DA:I, the romance plots (and companion plots themselves) really seem to be approximately in the same proportions to main storylines throughout.
The main plot, which includes all of the extra running back and forth between locations (dead time, even if it's combat and such. Good stuff, but it's only there to extend the gameplay, not the plot), and the companion content (including romances) seem to me to be weighted at around a 2:1 "main" to "companion" content ratio. This is a VERY broad generalization, and it's mainly my opinion based off my own personal experiences, but if for example you spent 30 hours in a playthrough, and did pretty much everything, you'd have 20 hours of "main plot" content (again, including the gameplay between plot advancing story sections), and about 10 hours of companion plot content (including quests, conversations, romances, etc.) Those are completely arbitrary, made up time estimates to illustrate my point, considering the differences in length between the various games.
The thing is, Bioware has always done a much better job of writing the 10 hour companion content versus the 20 hour "main plot" content, so it looms larger in the minds of the players. To me, this is one of the strengths of Bioware games. I'd much rather have characters I care about in a relatively mediocre plot, than a fantastic plot with characters I couldn't give two farts about. Obviously, the ideal would be a fantastic plot and fantastic characters, but I have yet to see a game that does that. And a terrible plot won't redeem wonderful characters, either (I'm looking at you, ME3!)
But, this is just my opinion. Your mileage may vary.