Although she still appears in the film it doesn't look like she accompanies the leads in any way apart from the scenes with the resistance gathered together, and according to some rumors she's mainly been reduced to a sort of supporting resistance character like Billie Lourd's Connix (In fact they seem to share a scene in the trailer). The lead-in comics and novels to TROS also seem to do very little with the Finn/Rose romance angle either. Some who have claimed to have seen the film say she doesn't do much apart from moral support and Rebel rallying, and some have said that Finn is pretty much back to having feelings for Rey and the possible romance is pretty much totally ignored. It also seems like her status as "the fourth lead" has been taken by either Naomi Acklie or Keri Russel's characters which have been used more heavily in marketing.
I've kind of reminded a bit of ROTS sort of dropping/ignoring some dangling plot lines from AOTC (Which were mostly later resolved in Clone Wars)-the whole thing with the Clone Army being ordered and Boba Fett's possible revenge for his father's death; or any plans Lucas originally had for Jar-Jar that perhaps were altered due to the reaction to the character.