Oh manga, why do you hurt me so? I know of your true intentions, that of Kosaki stealing Raku's heart in the end... so what the hell man? This chapter got soooo, so close.
I assume you meant Chitoge, here, not Kosaki, because this
was Kosaki with him on this work trip, the same girl he’s had a crush on since the beginning.
And, yeah, I‘m pretty sure you are right on that. Chitoge feels like the intended love interest. At the very least, I feel like I can safely say Raku will be conflicted between them before the end, and even now he’s likely harboring feelings for her without realizing it. I was particularly getting the impression with the mother arc, at the very least, though the first clue felt like as early as when Raku’s yakuza buddies locked him and Chitoge in the storehouse and she clung adorably to him.