Desvelo comes from the verb desvelarse, meaning to stay awake or to lose sleep. It's a more evocative word than simply saying "I can't sleep."
In the song, Tito Rojas sings, "Y por las noches si no estás conmigo yo me desvelo" (And at night if you're not with me, I stay awake). It beautifully conveys the depth of his longing and how his beloved's absence affects his peace, making it a memorable and emotionally resonant word.
"Siempre Seré" is a salsa romántica about loving someone you can only have in secret. The singer meets her again after a long gap, counting the hours they manage to steal, and he has no illusions about his place: he is the one who calms her longing and the tenderness that wakes her passion, but never the great love that first won her heart.
The chorus is where the ache sits. He would rather take the smaller part than lose her altogether, and he says it plainly. He will always be the comfort. He will never be the dream.
The long soneo section at the end is Tito Rojas answering his own chorus, line by line. He is the rain that wets her hair, the man who does not forget her, the one who forgives her when she has no love to give. It closes on a quiet call and response with the coro, a few words at a time, all the way to "hasta la muerte".
Tito Rojas, born Julio César Rojas López in Humacao, Puerto Rico in 1955, was one of the warmest voices in salsa romántica. Fans called him "El Gallo Salsero", the salsa rooster, and the name stayed with him for the rest of his life.
He sang in other people's bands first, with Conjunto Borincuba and the Fania All-Stars in the late 1970s and then with Puerto Rican Power, before going solo in 1990. The 1995 album "Por Propio Derecho" made him a headline act, and "Esperándote" and "Por Mujeres Como Tú" both reached number one on the tropical charts.
He kept recording and touring for three more decades, and was nominated for a Latin Grammy for his album "Un Gallo Para La Historia". He died in Humacao in December 2020, at 65.