I trust Vanessa about as far as I can throw the Titanic...
I also trust Vanessa to do more than tease Zara if she shows any affection towards the MC.
I've shut Vanessa down as hard as Ocean will allow me to thus far, but I still see Vanessa stirring up trouble on this front.
I think Vanessa views the world as a playground where she can toy with people and their emotions with little consequence to herself (I'm thinking of Nami in the hot tub the day before and Mila when she shows up at Nick's house needing a place to stay -- both interactions are ongoing, but Vanessa has made her initial 'play' showing 'interest' in both women).
I believe it will be up to the MC to shut down Vanessa once she tries to make trouble for Zara regarding her growing feelings for the MC.
I hope that the MC is eventually given the option to tell Vanessa that he would choose Zara over her every time and that he believes in Zara (reaffirming Zara much like he did when playing BB).
Cheers!!