I haven't played "Quaint" so I'm reviewing this purely as a standalone work. This is a great introduction that makes me interested to play the main game as well.
Love triangles in romance have always been a guilty pleasure of mine, although sometimes they can feel a bit silly when the choices are unbalanced: when one pairing has far more chemistry than another. It's a fascinating short thought-piece to see it explored in the multiverse scenario when you have to pick between the 'same' guy. Especially where the other version of Q might be in danger, or not, so it feels like a dilemma that truly matters. I enjoy Q for feeling human as well, that he voices displeasure for T leaving him and tries to convince you to pick the stay option, even if it possibly dooms the Other Q.
Very eye-catching to have the title screen change depending on which ending you picked to receive some continuum and make your choice feel heavier.
What's not told gives room for mystery too, like what's up with the previous T that got replaced by the T in this timeline?