The speaker is talking to someone who keeps hurting them, and the poem works like a series of labels. Each "If ___ had a name" gives a blunt, honest tag: the other person is "the Rain" because they bring storm clouds to people's eyes, their personality is "Confused" because they can't make up their mind, and the relationship is "Failing" because it feels as though the two aren't really together. Even the speaker's own name would be "Sad," since that's what this person has done to them.
The mood is heavy and tired, a little bitter, but not hopeless. The last stanza turns things around. The speaker calls themselves "Strong and Fighting" and says that's how they stay on their feet. The closing line, "But I know I can do better," is quiet but important. It could mean the speaker deserves better, or that they can push themselves further. Either way, the poem ends with self-belief rather than self-pity.