This is everything I wanted. All this time, whenever I thought about how Reiji and Nagi could pull themselves out of this despair, I keep thinking of how a heartfelt, romantic, and vulnerable confession of love might be the way to break Nagi's ice, seeing as that human connection is ultimately what she desires. Also, I kept thinking, they both share a connection and a desire to care for each other, they've clearly been previously intimate, so what if their abyss is terrifyingly deep, affection and warmth always have a way of combating the darkness and nurturing the small ember of light present deep within every abyss.
This is totally my hopeless romanticism on display rn, but I don't care, because that connection, sharing their pain and burdens, without having to carry everything on their own shoulders, has to be their salvation. There is literally hope for nothing else rn, that's how strong the metaphorical Abyss is in this story. It's the ultimate antagonist, surpassing even the likes of Yuko. As a Reiji x Nagi shipper, I'm on cloud nine rn!