Hi Carrot, thanks for the long review for this short story!! So far, I can tell from your comment that you got two endings out of the four, (correct me if I'm wrong lol), so it makes your perspective on it very interesting to read to me!
Basically, the endings you got (if I guessed them right) are obtained through two ways: pressure indeed and, more than acceptance perhaps, longing. Without going into too many details, you have three ways to play River: either as a character who isn't ashamed of asking something as selfish as going back to life as a 24-yo forty-eight years after his death to their husband ("Selfish" ending in the walkthrough); either as a character who doesn't have anything to ask, but suffers from the loneliness and just wants to tell their husband how much they love him ("Resurrection" ending in the wlakthrough); or as a person who's been trying to be strong and perhaps just need a push into the right direction to seize their life (Rebirth" ending from the walkthrough). And having River in a too confused position between these three poles leads you to the "Confused" ending in the walkthrough (I wasn't very inspired for the names looool).
So, I guess the least sad is the Rebirth one (but now I wonder if you got it since you kinda mention River having to learn to live for themself; while in the Selfish one, River goes straight to the river), since it consists in Ambrose going back to his shadows and River empowered by his nice words and willing to live for themselves again. But yes, the two outcomes you got are at best bittersweet: for Resurrection, we can just hope Ambrose shoulder better the fate River had to fate; for Selfish, well, I suppose the ending kinda puts a final dot to River's situation??
For the gender, let's say I wanted River being non-binary to hold some relevancy in the plot without making the story about it: basically, just to say that while being queer is an important part of them that can't be ignored, it isn't all of them, or at least, it doesn't have to be the drama in their life loool, for some reason, I feel like losing a kid and a husband would be more dramatic!
I'm glad you found the story thought-provoking and touching and thank you so much for your compliments on the technical aspects!! I really tried to give the game A VIBE loool, and I'm glad it showed! Finally, thanks for the nice feedback per usual, it is precious to me!