Well, to be honest, Ciri did not have a choice in this matter when it started. It was pretty much who rapes her first - a boy or a girl. A girl won the contest. As you remember, she did not feel too great when she washed in the river in the morning.
This. Ciri was at an extremely conflicted, complicated time in her life while that relationship lasted. She was orphaned, abandoned, lost, and her first sexual experience was pretty much non-consensual. Also, her experience with Auberon - a heterosexual experience this time - was also borderline rape (and in most countries, blackmailing a person into sex
is flat-out rape). That's enough to screw up any adult, let alone a teenager, so there's no way to tell how she will react to those experiences as an adult; and since we have nothing concrete to help us guess, whatever CDPR decides to roll with, as long as it's (and I'm not worried!) well written, should be coherent with the books. One very likely possibility, though, is that like many victims of such events she simply goes neither way and stays away from sex altogether. She has enough bad memories from both genders to give her nightmares for the rest of her life as it is, so you can't blame her.
Besides, honestly, I really don't expect Ciri's sexuality to come up at all in TW3. Let's not forget that her current occupation is running away from a horde of blood-thirsty elven wraiths intent on raping her. That's not a conducive environment to developing romantic relationships u_u