The issue with the ending is that even after scouring the game for every scrap of info you can find, you will end up knowing nothing about Red.
What's she like? What's her take on all this? What's her end goal? You hear a whole lot about what Sword Guy is feeling, but does she like him? Does she even know him at all? There's an opportunity for development toward the end of the game (!!) when she starts offering him encouragement through the terminal screens, but it's awfully generic. "I'm going to get you out of there!" etc. Nothing you wouldn't say to your dad. Hardly leaves the impression that she might, oh I don't know, blow off rebuilding the city to go sit on his corpse and kill herself out of longing and despair.
The final scene places Red's eternal love for this dead man at the heart of the whole game. That crazy end-of-the-world business was all in service to the story's emotional core. These characters' relationship is the A-plot and this is its climax. This lady is fundamentally unknown to us, and their relationship is being almost entirely established for the first time BY this action. There's just nothing to feel, it's totally unearned. I laughed, honestly.