Actually... shit... Just thought a bit more on this whole situation. I've admittedly finished the whole Manga at this point, but I feel like making a very vital observation:
If Raku had chosen Kosaki for real, I feel like his life would have been forfeit. The more I think about it, the more I realize there's far more 'strategic pieces' in place to ensure Chitoge's happiness than there are Kosaki's. Kosaki's support network is literally just regular folks. Sure, they're good people, but Chitoge has her share, as well, and the important thing is that her people are far deadlier. It's quite likely if Raku hadn't chosen Chitoge, Tsugumi might have closed off her heart and treated him as an enemy, meaning Raku would have to contend with both her and Claude coming after him for legitimately breaking their ojou's heart.
Raku could not have been able to deal with this situation. There's also the fact that his entire character is about connecting with and maintaining bonds with all these people he came to call friends, similar to Yui. Burning the bridges with the Beehives would have, at bare minimum, ruined his friendship with three people.
The only reason Tsugumi is on Raku's side in the real climax is because she believes so much in Raku's love for Chitoge that he will make her happy. Yes, she loves him, as well, but she loves Chitoge just as much, if not more. At best, in the event he rejects Chitoge, she would shut down due to the conflict of loving him and hating him for betraying her trust and hurting Chitoge so deeply, and then Claude would be able to act unopposed and destroy him.
This isn't just some simple love triangle/harem story. There's battle shonen aspects to the mafia side of the equation that must be accounted for in the flow of the narrative.
With this in mind, there really was only one possible result for the climax of this story, and it was pretty much evident the moment the story began, and only became harder to ignore the more Beehive pieces were revealed. Hoping for Kosaki Onodera to live happily ever after with Raku Ichijo was always going to be wishful thinking.
I will note this is not the first time I've noted that Raku's life would be forfeit if he broke Chitoge's heart in the comments- I know I've made the observation a few times during my first reading of the story. This is just me making a definitive determination in the comments section of a relatively middle point of the story.
So, there we have it... my prior post which highlighted the preponderance of emotional bonding time that Chitoge has had with Raku from the start thanks to the 'false love' situation that is the very title of the series, and this post that highlights the strategic backing around the gang warfare side of the story that makes it impossible for the shy girl's happily ever after with her first love.
It just wasn't meant to be, ever, in any way, shape, or form.
I suspect this is why the anime prioritizes so many Chitoge growth and relationship moments in the additional chapters, especially in Season 2. There's like 4 Chitoge-specific episodes alone in the 12-episode second season, and two of them are one of the best 'short' arcs in the entire manga, the Mother arc. The other two are literally the book-ends of the season. If there wasn't any greater indicator of Chitoge's role as primary heroine, I don't know what is. The fact the entire anime closes out on a double-dose of really touching Chitoge chapter adaptations in the final episode really speaks to her role in the story- 'The Search'/Ch106:'Investigation' and 'Just Testing'/Ch100:'Try'. Look forward to them, all those doing their first reading through this story.
Kosaki barely got one episode in all of the second season, tying with Marika and Tsugumi. Her own little sister Haru beats her out with one and a half to two episodes. Everything else was either group episodes, random shit like the magical girl shorts, or the epic Shu arc episode 'Support'.