Conjugué comes from the verb conjugar, meaning "to conjugate" verbs. It's a word you wouldn't expect to hear in a pop song, making it quite unique and memorable.
In the song, the lyric "Conjugué mal los verbos" (I conjugated the verbs wrong) is a clever metaphor. The singer isn't literally talking about grammar; he's saying he misunderstood or misapplied the rules of their relationship, leading to its failure. It's a poignant way to express his regret and self-blame.
Mijares's "El Único Culpable" is a really honest look at a breakup where the singer takes all the blame. He admits, "Fue mi culpa lo siento, No debí amarte tanto" [It was my fault, I'm sorry, I shouldn't have loved you so much]. He built up his partner, making their "suelo" [ground] into a "cielo" [heaven] and putting them on a pedestal. He realizes he expected too much, saying, "Esperé demasiado" [I waited too much], while his partner was only looking out for themselves.
It's a bit heartbreaking, but also really direct. He wishes his ex finds someone "tal y como tú" [just like you], someone who will treat them exactly as they treat others, because "al final cada uno tiene lo que merece" [in the end, everyone gets what they deserve]. He's accepted his role, declaring, "Hoy soy punto aparte, Y acepto fui culpable, El único culpable" [Today I'm a separate point, And I accept I was guilty, The only guilty one]. It's a powerful song about taking responsibility for your own choices in love, even when it hurts.