Desaba means 'collapses' or 'crumbles'. It's a strong and evocative verb that paints a vivid picture of something falling apart.
In the context of the song, it's used to describe the emotional impact of a relationship ending: "Coração então desaba" (The heart then collapses). This powerful imagery conveys the profound sadness and breakdown of feelings, making it a memorable and impactful word.
Gusttavo Lima sings about the exact moment a relationship crosses the line from painful to over. He opens with the title line itself, "Passou da conta, agora chega" ("It's gone too far, now it's enough"), because he can read the decision already sitting in her eyes before she says a word. From there he lists what's actually died: "O beijo não é mais gostoso" ("The kiss isn't sweet anymore"), "Fazer amor não dá prazer" ("Making love gives no pleasure"). No metaphors about storms or broken glass, just the physical stuff that used to work and doesn't.
The chorus is where he talks himself into leaving instead of begging to stay: "E dessa vez eu quero acordar sozinho" ("And this time I want to wake up alone"). He admits he'll still miss her, "Eu vou lembrar você" ("I'll remember you"), but pairs it immediately with "Mas tenho que esquecer" ("But I have to forget"), because "Nossos caminhos já não têm outra saída" ("Our paths don't have another way out"). It's a breakup song that skips the anger stage and goes straight to acceptance, which is why it plays so calm for a song about giving up on someone.