Despintada is an intimate word that literally means "unpainted," or more commonly, "without makeup on." It's used to describe someone in their most natural and vulnerable state.
In the song's opening, Junior H sings about imagining his love despintada and resting in her bed. This tender, private image contrasts sharply with his own chaotic "rockstar" life, highlighting his deep longing for a simple, authentic moment with her.
Junior H gives us a classic late-night heartbreak song with "MIENTRAS DUERMES". He sets up a big contrast right away: while his ex is sleeping, he's out "Viviendo la vida de rockstar" (Living the rockstar life), drinking and singing. But this lifestyle is just a front. The reality is he's miserable, admitting "No salgo de la depre" (I can't get out of this depression) and is paranoid that another guy is getting close to her.
He feels like their relationship, which he says "se murió pronto" (died quickly), was completely one-sided. He lays it out very bluntly: "Aunque fue poco, te lo di todo, y tú no a mí" (Even though it was short, I gave you everything, and you didn't). He's stuck thinking about her constantly, even though he knows she's probably moved on and is "soñando en otro" (dreaming of someone else). It's a lonely song about being surrounded by people but only wanting one person who isn't there anymore.