I feel there's a... chronological issue with the way the relationship with Yen was handled. Observe.
You meet Yen, and the game immediately tells you via dialogue that this isn't a smash and run relationship. From the way you interact with each other in Wyzima, to the first bed scene, through the main quest line, you're constantly reminded that Yen is important. Very important. In fact, most of the interactions with her boil down to reminiscing. We did that, we went there, wasn't that great, how we (mostly Yen) laughed, etc. And then the D'jinn quest ends and the whole relationship drops off a cliff if you pick one of the options (but in reality nothing changes because Yen is necessary for the rest of the game), or continues on without any change if you pick the other.
Now look how Triss is handled.
You meet her, and even without knowing anything about the events of the previous games, it's easy to establish you have a past that isn't really in the past, so to speak. At the same time, you're essentially free agents with the ability to pursue the potential relationship again, if you so desire. You do the quest line and in doing so, you can choose to grow closer or remain distant. The connection either grows organically or never takes off. As the end of the arc comes around, regardless of whether you remain indifferent or rekindle the spark, it all feels organics and, well... make sense. Because you made it make sense with your actions.
As nostalgic as the Last Wish was, I think it would have been better to handle the spell breaking as early as possible (perhaps even off screen, via some ex machina) and let Geralt and Yen figure the future out on their own.
