Are you honestly suggesting Bioware is going to write their protagonist into being a rapist-by-intimidation?
Deliberate intimidation? No. Unintended? Sure- it would hardly break precedent for unhealthy relationships. Bioware already gives you the opportunities to be a sexual predator (Vega), borderline sexual deviant ('almost a child'/lookalike taboo Liara), a victim of sexual coercion and exploitation (Morrigan), abusive (or exploitative) relationships (multiple), and a few other types of relationships that would be found upon if they weren't supposed to be portrayed as 'romantic,' like how the only therapy Jack needs or can get in ME2 was the magic **** of M!Shep.
Having a player cad enough to try to sleep with anyone when a 'flirt' option shows up find out that some people will agree out of fear of the massive engines of death, devastation, and potential petty vendettas that are the aggregate PC? Sure, why not? No one is making you act that way, any more than you had to kiss the tavern wench in DAO.
And I'm still not hearing an alternative. As the Inquisitor, you control a vast army to rival nations, a network of spies and assassins, and command considerably influence among nobles and merchants. It doesn't matter if they work for the Inquisition directly or not, by the end game there potentially quite literally no one in Thedas that you don't hold some sort of influence over or who wouldn't be somewhat intimidated by the power you could bring to bear. Maybe the Archon of Tevinter and the Black Divine or the Triumvirate of the Qun. That's about it. And even with them it's largely a matter of them being far away from you.
There are four alternatives I can come up with off the top of my hat.
One is to not have a romance at all. That's simple, and arguably the most professional for an always-on-duty but temporary role of the Inquisitor and Inquisition. Keep it in (or out of) your pants for the year or three the game covers.
Another is, as you reference, have a relationship with a relatively similar power base and position of power. The key word in this is 'relative,' not 'absolute.' A person of the nobility may be weaker than the Inquisitor, but not the same as a rank-and-file soldier of no station. A leader of a separate organization that may be weaker but is none the less autonomous of the Inquisition. Were the Templars or Mages allies instead of conscripted, that could be an example of a possible option.
The third, and this is specific to the 'don't screw around the chain of command' objection, is to have someone who isn't a part of the chain of command (or Inquisition). This is the more professional line of thought that doesn't care about power imbalance as much as inter-organizational foolery. A tavern maid, a bookish librarian, or what have you.
The fourth is to have some sort of pre-existing relationship that predates the ascent to power or was independent of the person's influence. In a Bioware game this would be controversial, but would be certainly possible as a role playing device. In an amnesia-trope game, it could be a pre-existing relationship that the PC (and player) has forgotten and must choose how to respond to. Or an arranged marriage that the PC was forced into, and chooses to make sincere or not.
So with that in mind, must the Inquisitor assume that literally no one in the world could possibly want to become romantically involved with them? They *must* take the blanket stance that anyone who apparently reciprocates their feelings is acting out of abject horror at the thought of what the Inquisitor could do to them if they refuse? That because of this position that quite probably was thrust upon the Inquisitor against their will, they must swear off all thoughts of love and romance?
Must? Of course not. There is no requirement that the Inquisitor be a moral person of sound sexual ethics and or professionalism.