My 2 cents:
The best romances comprising of substance that I have witnessed have been in TV shows. Each episode allows for character growth of individuals as well as evolution of interpersonal relationships. Overtime, writers push progression that feels much more natural. Movies, have been known to do a decent job as well but the long of short of it is that in both examples, the observer is a passive recipient.
In games, between aspects like moment to moment gameplay, core gameplay motivations and player agency, romance from ground up is truly a hard thing to do. It is why in Witcher titles (I have yet to play them myself) as far as I have seen, the devs were able sidestep this issue because of pre-existing relationship status between Geralt, Tess and Yennefer. The player is playing out the role of a person who has a bond with these two other characters from the books.
To the end this bit from the OP is something I have thought of for a long, long time:
One aspect that's always bothered me when it comes to fandom is the discussion of romantic/sex partners in games like Bioware games, Bethesda games etc. As the avatar probably gives away, I'm a bi woman, but I am not a fan of the "All Bi" thing some games do nor do I like it when non-bi people push for that or declare it's the only "correct" way of doing sex and romance in games. For me, so many games and people who argue for this treat bisexuality as nothing more as an easy game mechanic, a convenience for their fantasies to be allowed to have a sex with anyone regardless of those characters feelings, preferences, history etc. That doesn't feel like good representation to me, but fetishization of us. We Bi people are more then that. We won't bang you just because you ask or want us to and games really should treat bisexuality more seriously, it ignores that just because many bi people are attracted to men and women, doesn't mean we want to date men or women or NB people or even attracted to men at all but are to women and NB people. Or you know, a bi people may simply not be interested in you.
Honestly, I do believe that more credit is being given here than what is deserved. Intent-wise I do not even think Bioware/BetaShed titles even think of 'bi-sexuality' when making partners romanceable even if effect-wise it seems that way.
To me, it always stood out as these devs simply wanting to the players' avatar be attractive to "MOST" romanceable partners. The only thing of consequence are the choices the player makes through his/her/their avatar and not about creating an organic world where the most important/romanceable NPCs truly have sexual characteristics of their own. This is to ensure that the player does not feel like they are being roadblocked for making a choice at character select screen. Furthermore, it also would not surprise me if this is done to avoid any potential claims of bigotry (akin to how Ubisoft titles always being by proclaiming that their games are created by "a diverse group of people" as a buffer against criticism for their exploitation of real world struggles in the most hamfisted ways to sell copies).
Good romance requires controlled pacing and enough content that allows for believable character and relationship growth. Doing that from ground up in RPG driven by dialog choices (that also has do many other things) will generally lead to anything but real romance.
I have, unequivocally, come to despise the romance in Mass Effect over the years. It reminds me of strip poker. I can only wonder whether Bioware can craft systems of forging meaningful relationship beyond, speaking enough times w/the desired NPC, choosing the "correct" dialog responses and doing their loyalty mission. It would be a nice change if the NPCs were imbued with believable characteristics like sexual orientation that did not dissipate after laying eyes on Player's Avatar.
