Looking at your game UC2 I get where you're coming from and in part what the problem is. Your MC is introduced as a lesbian who is sure of her orientation but forced into a situation where she faces strong peer pressure and maybe even coercion to become at least bisexual.
In my experience peer pressure works best when the target is not yet sure of her/his/their orientation, but once a person has found their true feelings, it's pretty hard to change that. At "best" you can pressure them into socially accepted relationships but that would usually not involve any sexual attraction or even love. One should also keep in mind that that pressuring or forcing a person to act against their orientation, desires and values can seriously fuck them up mentally.
Then there's the fact that on the straight-to-gay-scale most people are located somewhere in between instead of at the extremes, even if they may want to pretend differently. The same goes for pretty much anything else.
Unfortunately my own weird life might provide a few examples: I grew up as a totally not normal boy in a conservative small town. My father was a prime example of toxic masculinity and when he was around (being a workoholic he rarely was) he would always try to feed me his bullshit about "becoming an alpha-male" and ridicule me for being the intellectual, nerdy type of guy. But the real problem was my religious mom, who valued conformity and what other people thought of you more than anything else.
For context: I am hetero-flexible, meaning I am primarily into women, have no problems dating trans-women and while 99% percent of my fellow men do not rouse my sexual interest, I am not revolted by the male body and really don't mind ending up with a dick inside of me or my dick inside of another dude during a threesome or group activities. Fun comes in many forms, so why limit myself to what other people find acceptable? And I am still at odds with my parents after all these years because I still reject the "married with kids and mortgage" lifestyle for myself, remaining unbound and indulging in my own pleasures instead of giving a shit about "the family legacy".
Now imagine me as an 11-year-old boy growing up in the last years before the arrival of internet and quickly realising that I'm not "normal". In my case, I am also a major kinkster and enjoy, among many other things, BDSM and latex wear. It's not something I picked up along the way, instead it was already part of my earliest phantasies, though lacking refinement due to a lack of available knowledge. Unfortunately, while I had no access to information on the "weird" thoughts I had, I had a mother who would make a point of ranting against "the perverts" (pretty much anyone who liked something else than straight vanilla sex) whenever she saw something regarding sex on the news. According to her, people like me (she didn't and doesn't know about my preference) should at least be sterilised if not outright sent to a gas chamber. Yep, that stuff can really fuck you up as a child.
But, the way peer pressure goes, I initially tried my best to be "normal". Give a cute girl flowers, invite her to the cinema, suffer through a romcom and when it finally gets to the fun parts after a few gruesome dates, we do some cuddly vanilla sex while my mind screams to buy her a latex outfit, tie her up and find mutually enjoable ways to fuck her brains out. Unsurprisingly, the whole thing didn't work out because I had tried to be someone I clearly was not and soon even the girlfriend noticed it.
The lesson: You can force yourself to act against your natural personality, but unless you have a strong motivation (money, power, not getting murdered, ...) you will sooner or later realise, that it's not worth the suffering because it will probably never feel good and natural to you.
What saved me in a way was my second, fairly short relationship. In a way we were more like best friends that star-struck lovers. We were both pretty kinky, but there were issues in our sex life that finally led to my gf coming out as lesbian. Like me she had been pressured by her family and the prevalent conservative values to force herself to be "normal". But while our shared kinks and friendship had made it easier for her to have straight sex with me and even get off sometimes, she admitted that at the same time she felt some degree of revulsion that she couldn't overcome. We talked a lot after that which really helped us both, remained good friends after our break up and suffered together through the bullying the country bumpkins treated us to after her coming out. Admittedly, she was the main victim, but I received my fair share as well since in the uneducated minds of many of those idiots my ex "would not have become a lesbian if I had given her a proper dicking" and stuff like that.
I'm happy to say that we both came stronger out of that and after we both fled to more civilised parts of the country following high school, she found her soul mate at the university and has been happily married to her awesome wife for more than a decade.
So, yes, you can pressure or force some lesbians (or homosexuals in general) into accepting a straight relationship but they will rarely find happiness in those relationships and sexual compatibility cannot be forced. It's really just like trying to get a straight person into a gay relationship.
Last but not least let me share the punch line of my weird upbringing: A few years after I left my old home behind me, my father came back earlier than planned from a short business trip. And just like it was some kind of cliche from the pictures he walked into a scene of my mom getting thoroughly dominated by her lesbian boss in the living room. Turns out my mother is actually a submissive bisexual and all her hatred of "sexual deviants" was just a mix of deflection and self-loathing.
I really should have taken a bet when I told my sister I was getting some weird sub-vibes from our mother. But I guess the feeling of immense satisfaction I got when my dad told me will forever be enough.
