At a café
You have talked well, your glass is empty, and you would rather leave on a high than stretch the conversation ten minutes too far.
The line for this moment
Alright, I'm off. Bye.
The Vietnamese for it, how it sounds to an English speaker, why it works here and not elsewhere, and what she is likely to say back with what to do next: that is what the pack opens, for this line and the others like it.