Personally, I see this as two people talking. The two were madly in love, but one committed suicide. The song changes POVs frequently and both heavily talk about death. One being metaphorical but the other being literal. When it mentions "afterlife" it is not talking about ghosts and spirits, but rather life after death; the life that others lead after the death of a person. In the first verse + first chorus it is the person who committed suicide talking to the other from beyond, rejoicing over how they succeeded. In the second verse + second chorus it is the living person mourning the death of their loved one, and feeling very suicidal themself, even attempting suicide a few times (e.g. "I try to escape the afterlife"). In the bridge, the mood changes, and the deceased person sees how distraught the other is over their death. During the third chorus, there are two things going on. The living person is trying to commit suicide again, and this time is about to succeed. (cont'd below)
(explanation cont'd) The other person sees this and is doing everything in their power to stop it, even trying to come back to life to stop them. The living person succeeds and the last chorus is them seeing each other in the afterlife. There is both happiness and sadness in this chorus, as they are happy to see each other again, but the first one that died is sort of asking the other, "How could you do this?"