How can you tell the difference between an "interruption" and an "end"?

Question

In the fill-in-the-blanks exercise I was doing, the sentence I didn't understand was as follows:

Nosotros continuamos con nuestra fiesta particular y estuvimos charlando y bebiendo hasta el amanecercuando me confesó que estaba enamorado de mí."

So it seems that "hasta el amanecer" was the "ending" of the chatting and drinking and that's why "estuvimos" was used.

If the sentence removed the until sunrise part, would this be correct because of the interrupting action ("me confeso")?

Nosotros continuamos con nuestra fiesta particular y estabamos charlando y bebiendo cuando me confesó que estaba enamorado de mí.

But what are some tips for how to tell the difference between an interruption and an end? Is the interruption always some kind of action? And the end is always a reference to time? It doesn't seem like it from the example in this lesson:

"Estuvimos almorzando hasta que acabamos con toda la comida y luego nos fuimos al cine.

We were having lunch until we finished all the food and then we went to the cinema."

Answer

Hola Melissa,In this long sentence:"Nosotros continuamos con nuestra fiesta particular y estuvimos charlando y bebiendo hasta el amanecer, cuando me confesó que estaba enamorado de mí." this last sentence with "cuando me confesó" is simply saying that he "confessed" when it was dawn. There is no interruption in this long sentence, as if it was saying "...at dawn, the moment he confessed..."With reference to the second long sentence:"Estuvimos almorzando hasta que acabamos con toda la comida y luego nos fuimos al cine."This is indicating the end of an action(until the time when we finished our food); sometimes the end of the action is not indicated by a "clear short time phrase" such as "de 8 a 5" or "el sábado pasado", but it is more wordy, as you can see in this example. The way we identify an interruption in a sentence is normally by seeing this sequence of tenses: "something was happening when something else happened", using the imperfect in the first part and the preterite in the second part after cuando; the way your sentence is showing:"Estabamos charlando y bebiendo cuando me confesó que estaba enamorado de mí." (We were chatting and drinking when [all of a sudden/unexpectedly] he confessed hi was in love with me.)I hope this clarified it for you.Inma