I get the impression the argument has more to do with miscommunication than either party trying to impose their view on the other. As is often the case with fiction, everyone is bound to have different interpretations of the same events, and the games allow the player to apply their own view of the matter however they see fit.
There are people who believe Geralt and Yennefer to be perfect for each other, kept apart only by circumstance and their own personal failings. And who doesn't have those? Others see their story as ultimately one of failed passion. Yes, they love each other, but they would never work out. There is plenty of support for either viewpoint in books and games, and I find discussing it to be interesting and in good fun. These things are never clear-cut, so there is no need to pretend people with a different interpretation are delusional or any such thing.
With the obligatory disclaimer out of the way, my personal interpretation is that Geralt and Yennefer's relationship is dysfunctional. Not abusive, not toxic, just dysfunctional, which is to say "not operating normally or properly." No matter how many romance novels and fairy tales promote such a setup, I'm having trouble getting behind a relationship where the two people involved are constantly breaking up and getting back together and cheating on each other while remaining utterly unable to develop similar feelings for other people, at least in the long-term. It reminds me of several sitcoms (if not all of them) which rely on exactly the same situation for seasons on end, and it strikes me as being just as unhealthy and frustrating in either medium.
So I feel inclined to agree with Thomas' approach to the scene from The Last Wish quest. Personally, I don't want Geralt to end up with Yennefer. I don't want him to end up with Triss either, to be honest. I don't think his dynamic with either of them justifies a long-term relationship. Admittedly, I dislike happily ever afters in general, but that does not preclude a protagonist ending a story in a relationship. I just like my fiction to be a little more open-ended in this regard and embrace uncertainty.