According to the online Oxford dictionary dialogue is: A conversation between two or more people as a feature of a book, play or film. Or a discussion between two or more people or groups, especially one directed towards exploration of a particular subject or resolution of a problem.
These are all great and I am the type of person who loves nothing more than a scintillating conversation with friends but for me the best type of dialogue is the silent one you have with your partner. You know when you can sit beside each other and just know what the other is thinking. Or when you are able to finish each other's thoughts and sentences. Those special moments together when verbal dialogue isn't necessary.
You can tell by his body language what kind of mood he is in or when you just know that tonight its on like a scone, just by his smile, a look or simple body language.
Those are special moments, with a whole lot of inner dialogue that only you two 'get' and you can have a meaningful conversation without saying anything at all.