Well, the way I see it, Triss is pretty much done with experimenting, she had more then enough of that and one of the things that drove her to Geralt was her disillusionment with purely sex based relationships. I feel like what she really wants is a serious commitment and if Geralt chooses her in the game, she pretty much gets that. From BoE:Yet another reason to stick to the romance option who's of a similar age and thus might at an approximately similar time feel that it's time to turn the relationship into a more or less asexual one - rather than to the immature little girl who still has half a century of need for experimentation ahead of herself.
As far as her erotic life was concerned, Triss Merigold had the right to consider herself a
typical enchantress. It had began with the sour taste of forbidden fruit, made all the more
exciting by the strict rules of the academy and the prohibitions of the mistress under whom
she practised. Then came her independence, freedom and a crazy promiscuity which ended, as
it usually does, in bitterness, disillusionment and resignation. Then followed a long period of
loneliness and the discovery that if she wanted to release her tension and stress then someone
who wanted to consider himself her lord and master - as soon as he had turned on his back
and wiped the sweat from his brow - was entirely superfluous. There were far less
troublesome ways of calming her nerves - ones with the additional advantages of not staining
her towels with blood, not passing wind under the quilt and not demanding breakfast. That
was followed by a short-lived and entertaining fascination with the same sex, which ended in
the conclusion that soiling towels, passing wind and greediness were by no means exclusively
male attributes. Finally, like all but a few magicians, Triss moved to affairs with other
wizards, which proved sporadic and frustrating in their cold, technical and almost ritual
course.
Then Geralt of Rivia appeared. A witcher leading a stormy life, and tied to her good friend
Yennefer in a strange, turbulent and almost violent relationship.