Be careful with differentiating cause and effect. I suspect we often find ourselves spending time in head-land because we want to avoid some uncomfortable real-land experience. The example of talking to the girl: it's a daring situation so we rather compensate by trying to think through all possible scenarios instead of facing the fear and just doing it. To prove that this is the case consider a pleasurable activity like playing a video game. In this case you won't stay much time in head-land but rather turn on the game and play some rounds in real-land without thinking too much about it.

I think it has a lot to do with Motivated Stopping and Motivated Continuation.

We keep on thinking if we want to avoid painful action, we do less thinking when the activity is pleasurable.