I bet even his next plan will also fail, seeing how his attempt at "perfectly planned suicide" is basically just middle school level plan with a lot of holes we need a very large gap of logic to even believe it will succed in real life...
As an ending of this story it's perfect though, his dumb plan failed and he's attempting to do another dumber plan. It encapsulate his whole life, meaningless and dumb. Also I don't have sympathy for Satsuki, she's the type of woman that will always chase after jerks against logic and will spiralling onto hellish life because she will stick with him even after he betrayed her again and again while she could've had moved on with her life (basically it's her own fault lol).