Hi there, it sounds like the answer is in your question ;) An exchange of queens shouldn't be "unexpected" or all that surprising if your attack would lead to a fatality. If the heat was on me I'd have no qualms removing the attacking forces if at all possible especially if material is equal. Perhaps in your future planing thier is an intermediate move you could make to sideline the opponents queen?
The victim of queen exchange !
Sort:
You are in the middle of the attack and feel pretty confident that in couple of moves you will finish your opponent... going for the checkmate...
Your are attacking and your opponent is helplessly defending..
Then suddenly the unexpected happens...
Your opponent forces you to exchange the queen (his queen and your queen) !
Suddenly your attacking plan is ruined....
It happens to me quite often.. and it is very frustating..
Any advice is very welcomed...