If I have another pressing engagement, or if the conversation has drawn to a natural end, or if the other person is personally offensive or disinterested in a way that indicates there is no productive point to continuing the conversation.

[Mun translation: 'personally offensive' doesn't only mean hitting on him, but... that's a lot of what it means. Though showing zero desire to talk to him would also work -- Enjolras doesn't push himself in where he's not wanted! Javert in-bar is an exception because Javert tends to march right over to Enjolras and actively interrupt him in order to be annoyed about talking to him, so... that one's on Javert, is Enjolras's opinion.]