I will go against the grain....and say, if you have the got the money or could save up I would go. Life is made up of memories of occasions like this, for someone to invite you to their wedding is an extremely special thing, it is a huge compliment to you that your friend views you as a super special someone in his life who he wants to share his and his future wife's greatest day with. I would probably either just take DD with you or go as a family if you have the funds and turn it into a fantastic holiday as well. You will have memories of this forever and I don't think you will regret it.