That's pretty much the only thing that bugged me. I absolutely loved the film, and everything seemed so well-paced. Yet, they meet in a bar and 5 minutes later they're planning to run away together? Am I missing something? It seemed way too in your face to not be intentional, especially when talking about Ingmar Bergman.
shareAs you can gather from the scenes with Monika and her family, later on in the film, Monika, IMO anyway, had already set her sights on Harry, because of the situation at home, and was looking to hook a man, a good one preferably (although she tries to tear him down). It seems to me she was sleeping around already, looking for the right prospect (witness the scene where Harty first walks her home and they run into one of her prior suitors). Anyway, that's what I think happened - Monika already had a relationship with Harry in mind before she asked for a light in the tavern.
shareAgree, Harry was her escape from her family. The fact that he fell in love with her and wanted to start a family was just a distraction for Monika.
shareGood interpretation. Make sense. Their relationship doom from the start, I think both of them wanted to run away from their hard life, maybe Harry little later in the film, after he meet Monika. In Monika case the desire to runaway is much stronger even when they didn't have anything to eat she still want to stay outside the "real" world. For Harry it was short youth revolt.
shareWell, some people do that in real life too.
And maybe it was more of a thing in those days. There are various movies in which somebody married somebody they just met on a trip or something.