The latest chapter (118) introduced a possible "keyholder" which is yui
if so then the 4 keyholders are complete
which then makes Chitoge the promised girl
why?
here ::
The Pendant was given to Raku before their separation 10 years ago
Onodera - she remembers playing with someone with a pendant (which means she isn't the one to give it to him = no the promised girl)
Marika - has a picture of her and Raku(wearing the pendant) while kids (same reason as Onodera)
Yui - obviously they didn't separate 10 years ago
there you have it, by the process of elimination Chitoge is the only one left as the "promised girl" (if Yui is a Keyholder, if not there is still another girl)
I voted for Marika ,but Tsugumi x Raku, coz Marika is mine