This person.... She was beyond gender huh.
More like fanaticism mixed with deep friendship. The genderchange only added in romantic element, but at the core, it was still based on a sense of duty and devotion.
Honestly, I get why he removed the ring. It was made clear that it wasn't a love based romance, or at least only a one sided one. The MC is either too dense to understand it, or too inexperienced to realize it. But the key thing is how earnestly they kept tacking on that it wasn't an engagement made out of mutual love. The MC never let it slide when someone thought she had any romantic feelings for Vincent, and would always clarify it on the spot.
It's clear to us as readers, and I believe that Vincent kinda gets it too. However no one who wants a healthy relationship wants to feel like they are forcing the other person to be with them when they so clearly and frequently state that they don't love them back, and are just doing it out of contractual obligation.
This hopefully will speed things up, but unfortunately, I can easily see one way that this story is going to progress, and its not, imo, a great path. The way I am expecting it to play out, it that this current situation will drag on for at least a few chapters of awkward drama between the two of them, their classmates who liked Leona, and the other noble girls. Likely the girls will all try and be with the prince again, making the other guys dislike MC in the process now that Vincent's bride has gone back to being a man. Vincent may even start seeing them as canidates, probably just to get it over with as his love doesn't love him back, because he still does need a partner regardless of who it is, or his feelings for them. MC will then either get jealous over the new girl spending time with Vincent, or frustrated with their inability to do what he does/lack of understanding of Vincent's quirks and habits to where he becomes a gatekeeper for Vincent, but this wont be enough for him to realize his own feelings, then he and Vincent have an awkward argument that turns into a confession/realization, and they become an actual couple because of it.
If this happens I will be disappointed, because this is just every single "I was forcably engaged to this person in a manner outside of my comfort zone" romcom's go-to plotline, just with a hint of genderbending for the hell of it.
The genderbending wouldn't even be a key factor anymore. And it honestly isn't even that important now. This could easily be a yaoi, yuri, or just a normal romance between a man and a woman, and nothing would be all that different.
For example, if the MC had just always a girl, things wouldn't be any different. Him being a girl or guy isn't the main point of conflict. This is just a superior/subordinate romance where the subordinate doesn't believe their relationship is real because of their difference in positions.