Just because it exists doesn't mean it is prevalent 
If we go by that logic, then we should scrap a lot of things from the real world "just because it is fiction". A Song of Ice and Fire is also fiction, but we can relate to the characters and the story because it borrows so much realism from European history, and in general, human experience. They have dragons too, but the setting is (largely) realistic.
This is a joke, surely.
What part of ASOIAF am I supposed to think is drawn from "real European History"? The Undead monsters? The decades-long winters? Or the absurd prevalence of slaughter and rape? The level of violence in the series is impossible for the "real-life" period on which the setting is supposedly based. Not only would people never have put up with it, it's simply not sustainable. If people had behaved like that in Medieval Europe, the continent would now be a blighted wasteland, incapable of sustaining life. No, GRR Martin deliberately crafted a fantasy setting that would allow his characters to behave so putridly, because that was the kind of story he wanted to write. It has nothing to do with realism.
Which characters am I supposed to be "relating" to? The brutal, rapacious, incestuous tyrants? Or the faceless dirt-farmers that get trampled under their horses? No, I don't find the characters of ASOIAF to be relatable.
Realistic doesn't necessarily mean it has to be borrowed directly from the real world.
Actually, that's exactly what it means.
Realism: the quality or fact of representing a person or thing in a way that is accurate and true to life.
Realistic: representing things in a way that is accurate and true to life.
To make the player's experience in a roleplaying game meaningful and relatable, you need to hit a couple of references from the real world.
Maybe that's what you need to make an experience "meaningful and relatable". But not every player is you. I don't are what you find meaningful or relatable. I don't need it, and I don't want it.
What I need to make my experience meaningful is the freedom and options to create my own character and craft my own story that were given to straight people, but denied to me by literally every single Bioware game prior to DA2, not to mention every other game throughout the entirety of history.
And who says I want a meaningful and relatable experience at all? What do vague buzzwords like that even mean?
I feel like making everyone bisexual is just satisfying the fans who can't get over that hot, virtual stud not wanting to cuddle with their male warden, or that enigmatic witch not wanting to kiss your female elf.
Oh, you feel? That's your argument? Feelings?
Well I feel that resticiting romances is just satisfying the snobs and bigots that can't stand the thought of sharing their pixel dolls with the icky gay people.
And you know what? I'm willing to bet money that my feelings are a more accurate reflection of "realism" and the "human experience".
Also remember that the system is going to change quite a bit (apparently), so romance and friendship will develop somewhat differently than either DA:O and DA2
I'm not the slightest bit interested in how they are going to develop. My previous interest in the feature at all is effectively null and void.