[Fifi's anxiety seems to abate, if only slightly: Bastien has never been unkind to her before, and though she doesn't know why Yseult would tell him, she has to trust it was for good reason.]

I, [she says with a fluttery, uncertain smile that doesn't quite reach her eyes,] I don't think so.

[She's still caught off-guard, which translates easily to scared; life has not been forgiving of her missteps, and what is this if not a misstep?
The smile drifts off, her face ashen, shamed.]

I'm sorry I kept it from you.