Raise hand 
That…from experience? often get peoples wanna kill X. Like you know? In Swtor, Lana beniko had a fling with Koth? Peoples killed him just for that lol
Peoples can be territorial, no matter if said fling or romance happen before Jeebus showed up like 40000BC 
I wouldn’t but at the same time I’m like…why do I have to see that? Unlocked achievement: Envious cause forever Alone
Meaning it’s fine, but it can give the player the Impression ‘‘You want me to see these two canoodling, and they are taking space and time you could have added that scene for my chosen romance instead cause them falling in love in front of me, doesn’t add anything…’’ NPC all over in a game world are supposed to have their own life even if they are programmed to just stand by a merchant all day long. And nobody care who they are and what they do.
So to add them, they have to have a role beyond ‘‘Thse 2 gotta smooche and you gotta watch’’.
As far as I can recall, the only game where you could have a couple in your party and you can barely react is in old BG1 game. Jaheira and Khalid are married and come as a package as companions. (Meaning you must take them both in your party or not at all). (Same with Dynaheir and Minsc). So they have a role bigger that kind over shadow their marriage and it isn’t like in your face…very subtle done.
well yeah.
Like in DA2, wanna romance Aveline…yet she become fast friend with Isabela. You can romance Isabela, yet hit all those Heart Flirt with Aveline while you do her Marriage Quest… 
The issue is that, at least from my own experience is that at least with Bioware games, they often wrote those things (romance) where the MC is the center of attention. And peoples got addicted to that to the point (Wahh why I cant romance my sister Bethany, she is hot! or the Arishok LOL) (Not me…but you know lol)
So even friendship has to be eclipsed by the main romance.
Just telling you what I saw over the years that’s all.
Thread like this give you something to chew on, but don’t let that change the core of what you wanna write and experiment and challenge yourself writing. I say, do it. Take feedback afterward like you did with ‘Creme de la creme’, and go from there.
Edit: Also btw, a rival-friendship thing has more ‘Use’ than say playing Match maker (at least to me, since I don’t feel right having a say who can date who). In a rival-freindship thing you can like egg someone on or play the moderator or medium or whoever you call it and you can add consequences. Like you egg someone and they do something stupid and it backfire on you and everyone is grounded.
But with romance? What I’m supposed to do? He isn’t good enough for you? Wanna come to my tent? yeah not my thing.