Student or Learner
I cannot go to a wedding party because I might be out of town then. Besides, I don't know his other friends and relatives. How can I say politely that I may not go to his wedding party?
thanks very much
In our culture, you receive an invitation. You return it saying you will come or you will not.
You don't get to decide at the last minute whether you will attend or not. If you are a very close friend of the couple, you may be able to say "I'm so sorry, but I'm supposed to be out of town for work at that time. If that changes..." and then they say "If that changes, of course we hope you will come!"
Did you not receive an invitation? Were you asked verbally? If so, you simply say "I'm so sorry, but that is on a date I'm supposed to be out of town. I'm sorry to miss it and I wish you both all the happiness in the world."
I'm not a teacher, but I write for a living. Please don't ask me about 2nd conditionals, but I'm a safe bet for what reads well in (American) English.