Peros literally translates to "buts" or "objections." While pero (but) is a common word, its plural form peros is less frequent and more intriguing, especially in this context.
In the song, Ruggero sings, "Que no ponga peros, ese fue mi error" (That he doesn't put buts/objections, that was my mistake). He's expressing a desire for his ex-partner to find a love that is straightforward and without hesitation, unlike his own flawed love which was full of 'buts' or excuses. This usage makes the word stand out and adds depth to his regret.
Ruggero Pasquarelli's "Probablemente" is a heartfelt look back at a relationship that didn't quite make it. He's owning up to his part, admitting that what they promised each other "se quedó en palabras, no queda nada" [stayed in words, nothing is left]. He knows he wasn't what his partner expected, and that he fell short.
He even tells his ex to blame him if anyone asks, saying "fue mi locura que nos separó" [it was my craziness that separated us]. Despite the pain, he wishes them a "amor sincero" [sincere love] – something he feels he failed to provide. The song is full of that bittersweet longing, as he wonders if he'll ever see them again or if they'll forget his name, even though he's "muriendo por verte" [dying to see you].