Rosie

I view this song as a casual relationship that has gone to the waste side. The line where he says he's drunk again and asks Rosie to come get the door again seems to imply that it used to be the norm for him to show up later in the evening for the sole purpose of being physical (due to the later lines where he asks her to take him back to her room to sing him her tune).

There also seems to be another man involved in the situation; maybe Rosie is in a relationship now or maybe she has moved on to being in other casual relationships, but he is well aware of the other man/men and doesn't care (based on his line about her not needing to hide his things), which I feel further speaks to the casual nature of the relationship. If he doesn't care that she's with other men, there doesn't appear to be too much investment there.

Lastly, I'm a fan of the lines "Perdon and lo siento, see, I learned those words for you." Roughly translated, it means "Pardon, it was an unfortunate accident." So, clearly, something happened to break off whatever relationship was once there since he is attempting to apologize and because she had clearly cut him off at some point due to the said incident.

In all, I just think it's a depiction of late-night desire for someone you once knew and shared time with; it captures that hopeless nostalgia we can sometimes experience after drinking.