These three poems are not directly connected. "Stopping by Woods on a Snowy Evening" and "The Road Not Taken" are single poems, while "The Pasture" is part of a larger work and is more meaningful in context. However, there could be a common theme of loss, or the feeling of having missed something/someone in life.
"Stopping by Woods..." has a clear sense of desire for something the narrator is missing. The famous lines:
The woods are lovely, dark and deep,
But I have promises to keep
--show that the narrator wants something more than the "promises" he must keep in his daily life. He wants the simplicity of the woods and the dark night, not the constant hassle of travel and work.
"The Road Not Taken" is the most classic example of this theme. The narrator here has taken a specific path in life, and contemplates what, in his future, he might think about his choice:
I shall be telling this with a sigh
Somewhere ages and ages hence
However, he is committed to his path, and understand that his choice has affected his life for better or worse. However, in the future, he might wish he had a second chance to take the other path.
"The Pasture" is a simple poem of eight lines, describing how the narrator is going to perform some farmyard tasks. At the end of both stanzas, he repeats:
I sha’n’t be gone long. -- You come too.
It is possible that he has already lost someone in his life, and doesn't want to be separated from this other person, not even for the time it takes to rake leaves.
Each poem contains themes of desire and wanting; the narrators are missing something and are either searching for it or lamenting its absence.