I'm not sure why they didn't include Yennefer in the first two games, but they DID allude to her existence and importance to Geralt in both. I am purely speculating here but it could be possible that they always had a trilogy in mind with the underlying story of Geralt separated from his long lost love with an eventual reunion in the last game.
Again I think if that was the case, being book readers it may have made perfect sense because after all they knew all about Yennefer from the books. but if you look at it from the perspective of someone who only plays the games it doesnt make sense because Yennefer is never really introduced in such a way to over shadow Triss who is physically present. They only teased the player with small bits of information about Yennefer and why she might be important to Geralt, bits that only a book reader might fully understand.
So now in the last game you have this problem with Triss who has become a much larger more identifiable character than they originally intended, but only from a non book readers point of view. But this is pure speculation by me trying to put myself in the position of someone who was tasked to write a trilogy based on characters I already knew well in the books.
Whilst I'm an avid reader in real life, I'm not fond of reading journal entry after journal entry in a game just to understand its setting. There are better ways to introduce new audiences to your world. As a result of never reading the books, I had no idea who Yen was. I'd had no exposure to her over the last two games, with my love interest being (from a story perspective) Triss. I'm then expected to read pages of journal entries to fill in the blanks of this person I'm being forced to romance in the game despite the person I've romanced in the last two being available to romance. As a result of the clumsy way she's introduced to the series, I felt no connection with her.
Nonetheless, if you do read the journal entry for Triss, you'll see there is only half a sentence referencing the break up. No explanation as to why or on how or were they parted, nothing on the Rose of Remembrance, confessions of love or promises made. Neither does it reference any events from TW1. So even if you are willing to read the journal entries for the characters, it makes out as if Triss was nothing more than a footnote in Geralt's history, someone he had a fling with rather than a true romance. By comparisons, Yennefer's journal entry has numerous references to their love and providing more extensive history between the two. It is clearly designed for players who never played either of the previous two games.
Idea of a forehead kiss is sweet
Just to point out, I don't think it is a forehead kiss, I think he kisses her on the lips but the animations aren't lining up correctly. It's a "Hi honey, I'm home" kiss. Just my opinion.
Patience is key here. Remember that Triss waited many years to finally get her chance, so if anything, follow her example.
