Where could Mr. Mallard have been since he wasn't on the train in "The Story of an Hour"?

The answer to this question is highly speculative because
we know very little about Mr. Brently Mallard in Kate Chopin's short story The
Story of an Hour.
We can only speculate because the entire story is
told from a third person narrative omniscient point of view that explores merely the
feelings and emotions of his wife, Mrs. Mallard.

We do know
this: Brently Mallard is the breadwinner of the family. We know this because it is clear
that Mrs. Mallard stays home all day due to the weak heart condition that she
has.

We also know that he must work far enough to need to
use a train to commute, being that the story is set in the 1800's during times when
engaging a handsome or a cab was the most common method of
transportation.

The last thing we know for sure is that he
is not dead, as everyone assumed. We know from the story that he arrived home late, but
also

"a little travel-stained, composedly carrying
his grip-sack and umbrella"

This could mean that
he was late coming home because he is probably working extra hours in order to be able
to keep his household and his sick wife. We can also assume that he missed the train for
being late, therefore, he had to walk half the road in order to make it home whenever he
could.

It is highly unlikely that Brently Mallard was
cheating on his wife, nor doing anything improper. After all, he seems to have a genuine
concern with getting home to his wife. Hence, chances are that the poor man simply got
caught up at work, and had to walk home all the way, or at least half of the way from
work.