Ahhhh Nagi came to stop him from swinging the blade!!! She followed him all the way here!
Also holy shit I didn't realize Reiji had the blade pointed towards himself until I read the comments. I thought he was about to kill Mao and that's why Nagi stopped him, because she doesn't want Reiji to kill Mao for her. Then I had to go back and properly look at that second to last panel and yep, this dude wanted to kill himself on impulse, while leaving Nagi behind (something I'm sure Nagi isn't thrilled about, especially after he made her promise not to kill herself before him, the audacity lol).
But I finally feel a glimmer of hope once again in this manga after previously losing it, for a happy ending. Hopefully Nagi saves Reiji, he lets his murderous urge against Mao go, and they both leave town together, heal, and become each other's salvation. Since Sensei Shiba finally seems to have regained her marbles after reflection on her downward trend into her Abyss, moving on from Reiji and letting Nagi go so she can reach and stop Reiji from becoming a murderer or in this case, killing himself.
Please don't disappoint me, author-san. If Reiji and Nagi don't survive and rise past their Abyss, then nobody would've learned anything and this entire narrative would've been for naught. Apparently she prioritizes events in terms of "what would the characters do next" instead of "what is needed for a good story/readers" when writing, but I can only hope she doesn't follow that rule too much when making the ending of this series. Please let all my effort reading this to pay off with as wholesome of an ending this series can muster, please. Let Reiji and Nagi find peace in their love for each other, WITHOUT KILLING THEM/LOVERS' SUICIDE.