I believe this movie came out around the mid to late 80's. It also might be a British movie. It's about a young couple being married by accident.
PLOT; A prince comes to the US to attend college where he becomes good friends with another student. Then the prince takes his friend back to Europe with him. (Can't remember why)
While in Europe the friend meets the princes sister who is engaged to be married. During a rehearsal the friend stands in for the groom and is married to the princess by her grandfather who is an old vicar, and who preforms a real marriage ceremony.
The friend then decides he doesn't want a divorce.
I've spent more than a few hours looking for this movie on the Internet, but haven't found it yet. Any help with the name of this movie would be greatly appreciated!