I was myself a bit harsh when I wrote my initial comment. I was rather irritated from seeing the work the author put into doing something original and thoughtful and most comments on the situation being only requests for Leo and Chase to end up together.
What I meant at the end by "almost impossible while they're together" is that they tend to keep each other in chains while they're near each other. They're a bit too taken into nostalgia and honeymooning to take the issues seriously until it becomes overwhelming. They could go to couple's therapy or something, but I don't really see them making that decision until they've reflected on what happened and grown more, and I'd see them only be able to do their personal growth while apart.
I don't think it is actually impossible for them to be together, but the thing that would mostly aggravate me about such an end being present is that it would reinforce the feeling of that ending being the "good ending" and the others being the "bad/normal endings", demeaning their value in the end, as the true goal would be to find a way to have them be together. I am a hopeful romantic at my core, and I was pining for them to be together, until I saw the ending and reflected on what lead to it. I just think such an ending would be a disservice to the overall narrative.
If someone wrote a fanfiction about them working through their issues and maturely growing to become a functional couple, I'd be all for it, but I don't think it's the type of narrative most common for fanfiction unfortunately. I still don't think it would be the best to include it within the game itself.