Is he "out" at work? if not, then this could cause even more than the usual issues....
The big issue is what happens afterwards - after the relationship has come to an end, which may or may not be very messy. Is there going to be massive awkwardness, or one or the other having problems getting promotions?
Please check out The Birdcage - an open, friendly Polyamory forum for all parts of New York State
"Listen, or your tongue will make you deaf." - Native American Proverb