Depends----
short term affair-
Go ahead if ur boss is cool with it.One of the issues is do u keep it under cover or be open in the office about it.I dont think many bosses would be game to the second option.
Can b in a dilemma at times of appraisal,promotion,etc.
If u are clear that this is all for time-pass and u can keep it under wraps,go for it

.(tumhara bhi yahi idea tha na?

)
Is it going to be long term?? If so u have to be really serious and understand the entire situation.Or else life can be seriously.....
Both of u working at the same place,24*7 can be boring.
Wife as a boss as someone mentioned can hurt some people's ego in the long run.
(i dont understand how?? If I have a wife who earns more than i do,I would take her to dinner,and sweetly suggest that I need to spend more time looking after the house)
Spend time observing ur boss(dont stare too loong) ,find out what she feels about you.Does she give ghaas?? If so,take one step at a time.