Soyinka gives us a pretty legit tragic ending. Having failed to bring off the suicide, Elesin is completely disgraced—it's quite a fall from where he begins the story. This fall is embodied in a shift in the way Iyaloja treats him: Though she was once super accommodating and deferential, when she comes to the prison, she verbally kicks him while he's already down. Iyaloja isn't willing to cut Elesin so much as a centimeter of slack, harping on his weakness and promising super bad consequences for him and the community as a result of it.
And then some men bring in a package, and it turns out to be Olunde's body; it seems he has sacrificed himself to try to take his father's place in the ritual. Elesin is devastated, so he strangles himself with the chains binding him before the authorities can react. While Elesin was always supposed to die, instead of dying with honor, he ends up dying in embarrassment and terrible grief. In all, it's pretty sad stuff.