It's wrong to cause problems at another person's wedding.
Tom's ex-girlfriend, Linda, is marrying someone else, and he has been invited to her wedding.
Tom wants to let Linda know that he is hurt and angry that she is marrying someone else.
Tom declines the wedding invitation, and he tells Linda that he has not gotten over their relationship yet, so it isn't a good idea for him.
Tom drinks too much at the wedding and blurts out, in the middle of the wedding party, that he hopes the marriage fails.
Linda is understanding when he explains his reason and Joe gives himself some more time to work through his feelings.
The newlyweds and all of their guests are shocked and angry, and Tom is embarrassed that he made the remark.