Cara and Nikki react allergic to fisical violence, and therefore they shoo you away, the right choice is to end up without violence,
which I did, the other "Landmine" is Julia, if you go to the club, and she aproaches you, don't give in to her seduction.
after you leave Riverside, Nikki or Cara comes to visit you, and you have great times,
Remeber it is a Monogamus game with a lot of hot LI and it is written from a womans perspective,
so much to the dificulty level of this game ....
Edit: What Maviarab said™