Hey Pandas, Ask A Question About LGBTQ+ And Allow Commenters To Answer It

I'm LGBTQ+ myself and I have a question. (For context, I'm Omnisexual, which means I'm attracted to anyone.) How does it work when, for example, there's a straight couple but then one transitions. For the cis person, do their feelings just go away? Like I said, I'm Omni, so I don't understand this. :)