Both share way more elements in common than two random shounen shows. Digging into the preferences, sources and/or backgrounds of the author of Nisekoi, how much of Love Hina's influence can be found?
Both shows have the following in common:
Childhood Marriage Promise: The centerpiece of both plots is a blurred promise. Love Hina's is both a marriage promise and a college proposal, but has almost the same weight. Note that several other animes (hit TVTropes for the list) have it too, but not as the centerpiece for the love story.
Naru and Chitoge are almost the same person.
- Tsundere? Check.
- In love with the lead male? Check.
- Denies affection to the deathbed? Check.
- Hits lead male when some gag puts them in an awkward situation? Check.
- Hair antennae? Check. (Chitoge's is actually her headband, but is indeed an antennae).
- Probably the one that made the promise? Check.
Raku and Keitaro are similar too, but as far as shounen lead males go, they are all the same person by design. So not too much here.
My point is, if you swap the Nisekoi setting from a high school to a boarding house, and remove the Romeo & Juliet elements, you have Love Hina.
Looking for credible sources.