One way to interpret Raku's birthday gift to Chitoge is that the doll is supposed to symbolize her. The doll has gorilla-like characteristics, but also a cute, feminine side to it.
Re-reading the story recently, I realized that the reason Raku is so incapable of noticing when people are in love with him is because before he met Chitoge, his yakuza family was so overprotective that they would threaten anyone who even came near him. Because he's been so sheltered by his family, he's simply incapable of noticing that someone is interested in him.
Raku's feelings for Kosaki can be explained in light of the other events of the story. Yes, they knew each other as children, and yes, she's the girl that most of the guys in the school are crushing on, but most importantly, she represents normalcy to him. His justified anxiety over the situations his dad and the Yakuza have created have resulted in him desiring nothing more than to marry Kosaki, change his surname to Onodera, become a civil servant, and never hear the following words again: Yakuza, Beehive Group, Mafia, SWAT team, assassin, and sniper.
And considering his choices were between two Mafia Princess, a police chief's daughter, a hitman, and a shy, clumsy girl, it sounded like the least chaotic option.
Raku's dad making an arranged marriage with Marika's dad between their two children makes no sense when you first look at it, because under what circumstances would a chief of police, especially one as protective as Mr. Tachibana, marry his beloved daughter off to very prominent gangsters? The answer lies in Japanese history, mainly the nobility. The Ichijo, named after the first street of Heian-kyo (Kyoto), are the senior branch of the Fujiwara clan. The four great noble families descended from emperors are the Fujiwara, the Taira, the Minamoto...and the Tachibana, and the Fujiwara and Tachibana were allied. Specifically, during the Genpei War period, where the Taira and the Minamoto were busy bashing each other's heads in, the two families married into each other in order to deter either side from bringing them into the conflict. Raku's and Marika's parents didn't come up with this plan out of the blue; they were doing what their families had done for centuries. Although, what a noble family is doing as Yakuza raises another set of Fridge Logic.
Maybe they went rogue and turned to a life of crime?
The storybook is very important to the plot because of its similarities to and inspiration of the plot, but what may turn out to be even more important are the subtle differences between the storybook and the plot. In the storybook, there are only four girls, including the princess, but in Nisekoi's plot there are six. Also, the storybook only has one key, whereas the plot has four. These could be instrumental in Raku's rewriting of the ending.
Why would Ruri have Raku pretend to be her boyfriend, rather than Shuu? Because Ruri's great-grandfather is way too pushy, and Shuu is a pervert. Put the two together, and it would be a disaster waiting to happen.
She picked Raku at random from her class registry, she wasnt even aware of it until afterwards.
Why did Shuu have a crush on his teacher? Because she's at least as big a troll as he is, and he couldn't help but admire someone who was so good at trolling.
At one point, Marika says that she hates girls with long hair, despite having long ones herself. Come several chapters later, we are introduced to Yui Kanakura, who Marika really despises. Yui's defining characteristic? Her long hair.
Raku's Shut Up, Hannibal! in response to Claude saying him locking Chitoge up until her flight to America was for the sake of "a bright future she has ahead of her" takes a whole new level of awesome when one realizes people wanting to decide Raku's future for him as the Shuuei group boss is one of his biggest conflicts. One can't help but wonder if Raku's speech about Chitoge's future being hers to decide was his way of telling himself the same thing about his own situation, and also him releasing his own bottled-up feelings about his own predictament, given how similar his and Chitoge's backgrounds are.
The title Nisekoi, Fake Love, can refer to three things in the series.
The first is obvious, the fake relationship between Raku and Chitoge are forced into.
The second is what Chitoge said in chapter 227, she isn't Raku's promise girl and is a fake. But Raku still fell for her anyway.
The last one is Raku and Onodera's mutual crushes. How it wasn't true love, in other words it was Fake Love.
In the manga, but anime especially, there is an episode (or mini chapters) showing Raku's married life with all of them. This is before Raku even realized his feelings for Chitoge, but if you look at it, it may seem like he subconsciously knows. Because in each life, he had a dog that was clearly representing Chitoge. But there weren't any other pets representing the other girls. But in each married life, Chitoge was there. Maybe meaning that subconsciously he cant imaginane a life without her. Because no matter what girl he was with, Chitoge was there.
When Chitoge and Marika are trying to hit Raku with charmed arrows, Chitoge is specifically told that those arrows didn't have much demand because how much they hurt. Onodera specifically points out that the arrow only needs to touch Raku for the charm to work. But that realization never hit Marika and Chitoge in their love-driven craze, who are desperate to hit Raku with the arrow for better chances with Raku, and actually fire the arrow at full force, completely unaware of the fact that those are REAL arrows. Now imagine what would have happened if Shuu didn't dive in front of the arrows mid-trajectory and Ruri catch them...
Well hes been shot at with guns before for comedic purposes, why are arrows more troubling?