Weddings are important to Marguerite because weddings represent joy and happiness and she wanted to have that feeling throughout the rest of eternity. She also wanted to be in the weddings because it brought back the memory of her and Eddies wedding and she wanted to hold on to that forever. Life doesn't last forever but love does, love carries on forever no matter what.
Ruby taught Eddie about the importance of forgiving people which led to Eddie forgiving his father about all that had happened when he was alive. Ruby showed Eddie all that had happened in his life that had to do with his father, even his fathers death which made Eddie feel the need to forgive his father. Forgiving his father lifted weight off of his shoulders and made him fell more at peace with what had happened.
The power of love to Eddie didn't mean much at first. Marguerite taught Eddie how much love really meant and how it changes when someone dies but will always be there. When Marguerite died Eddie thought he would never love anyone as much as he did Marguerite. When someone dies the love will always be there and to Eddie his love for his wife was more pain for his loss and love for his wife. The power of love is important to anyone even when they are dead or right in front of you.