'a sad reason' is a correct and usable part of a sentence in written English.
It is typically used to refer to a particular cause or explanation that is emotionally distressing. For example, "The loss of his job was a sad reason for their move across the country."
Nowadays it is the BRIC countries Brazil, Russia, India and China that have all the swagger, while Mexico commands attention for a sad reason: the surge of drug-fuelled violence that assails some of its cities.
And KateNonymous (who, just as an aside, gets bonus points for having one of my favorite commenter monikers) had a sad reason for keeping the news of a pregnancy to yourself under these circumstances: shortly after deciding not to tell a job interviewer that she was pregnant during the interview process, she lost that pregnancy.
"You are happy your friend has come, but it is for a very sad reason".
BOSTON RED SOX 2013 WORLD SERIES COLLECTOR'S EDITION ($69.99 BluRay; A&E/Lionsgate) -- If for some sad reason you're a Boston Red Sox fan, this set brings together season highlights and all six games of the first Boston World Series to be won at home since 1918.
Now, however, for the wrong and very sad reason"the Sept. 11 tragedy"international cooperation seems to be making a comeback.
The Body is almost certainly the least Buffy-like episode of Buffy, and with good, sad reason – it's about death.
When we like people, for some sad reason, we can convince ourselves that it is reciprocal, no matter how obvious the truth is to everyone else.
Though the mood of the first act turns melancholy, as the sad reason for the departure of Russ and Bev is revealed, the play's contrasting second half is bitingly comical.
Vanity is the sad reason why people don't wear bike helmets.
"Despite the very sad reason we're all here, the sense of community spirit has helped people soldier on.
Another sad reason for yesterday's events".
