Others understand me, why can't you?I never said that Shani went into the wedding thinking that this was going to be a one night stand. She posted a note on one of the bulletin boards near Oxenfurt which said that she was looking for a gentleman to accompany her to a friend's wedding, and that if he behaved himself, she might let that person court her properly. Fortuitously enough Geralt shows up, someone who, depending on player choice, might have had previous romantic dealings with her. So yes, I agree, she was not looking for a one night stand, she is potentially looking for a committed relationship and a man that she can settle down with. What I don't agree with is the assumption that just because she and Geralt might have once been an item, and because they decided to rekindle that romance at the wedding, that it is now incumbent upon Shani to make something permanent out of it. She said "I need to sort this through in my mind," as you yourself pointed out, which is obviously an indication that she has mixed feelings about what just happened. There are a myriad of different reasons why she might not want to marry Geralt, despite their previous romantic entanglements: he's infertile and incapable of having children with Shani, his lifespan is significantly longer than hers, he hasn't proven that he is capable of commitment and subordinating his own interests to that of another person (yes, Geralt eventually does just that with Yennefer or Triss, but Shani has no way of peering into those other potential realities.
You keep mentioning choice, how it is removed from the player despite the developers presenting this as a potential romance. But what about Shani's choice? You're basically saying that relationships in the world of the Witcher break down into two groups, flings and marriages, that all characters must fit neatly into these two categories, and if a character is not a fling then Geralt must have the option of marrying them. That's pretty twisted logic and way oversimplifies how relationships work.
It has everything to do with character development, story, and reading between the lines. Video game romances get a bad rap precisely because realism is relegated to the back-burner in order to accommodate player choice. In some ways this reminds me of the debates over npc sexuality over on the BSN. You would fall into the camp that says, "It only takes a few extra lines of code to make an npc gay or straight. Why not make everyone happy and create exclusively bisexual characters?" I would retort, as I seem to be doing in your case as well, that relationships do not work that way in the real world.
Anyways, I don't think we are going to arrive at a consensus. It's pretty clear that you conceptualize video game romances in a completely different way than I do. You seem to prioritize player agency, whereas I believe that developers should try to mimic the complexities of real life relationships, even at the expense of player choice.
1. Shani romance is presented as a relationship.
2. Shani states clearly that she wants a stable partner in her life, someone she can "come home to".
3. Shani specifically rejects a relationship with Geralt on the basis of him being on the road.
4. This is the inconsistency because in the other two relationships Geralt does settle down and retire.
5. The inconsistency is caused because the dialogue options do not allow Geralt to say he is ready to retire and settle down.
Whatever he does after that is irrelevant. Whether or not she does or does not agree with him, does or does not pursue a relationship with him is up for debate. Had the option been there to have Geralt state he was ready to retire and settle down with Shani and her not believe him or any other reason not to pursue the relationship then it would at least still be consistent with the other romances. Because it doesn't, it isn't.