I've read that as well but always taken it as obligations which need to be fulfilled.
I think this poem is great because of the multiple interpretations. The “darkest evening of the year” could refer to despair or to the actual darkness outside. Why does the horse shake the harness bells? Did the horse really think it was “queer” to stop there, or was it the traveler’s own doubts? I’ve never figured that out. I think that your interpretation is also valid. I’m glad this was posted this morning. Interesting.