During the summertime, months of July and August, you might be lucky enough to be invited in a traditional wedding in Anogia, the traditional, highest altitude village of Crete island
I you happen to be in Olympos, during August, you might be lucky enough to witness the transportation of a groom's dowry to the bride's place before their marriage. A very old traditional custom
If you happen to be in Olympos village of Karpathos island during August, you might be lucky enough to see a traditional wedding taking place. I was able to see both a wedding and an engagement.