Handfasting is a ritual involved in many Pagan and Wiccan marriage ceremonies. Originally, in the time of the ancient Celts (from whom the tradition originated), the handfasting ceremony began a trial period for a couple; its purpose was to let couples see what it was like to be married to one another, and be given the opportunity to decide if it was something they wanted to do. Traditionally, at the end of a year and a day, the couple could either choose to part ways, or to become permanently married. Now, things are done a little differently. Handfasting today can either be part of a legally-legitimized wedding ceremony (complete with catering service), or can simply be a statement of commitment “as long as love shall last” (as opposed to the Christian “til death do us part”). Some Wiccans believe that this trial period be begun on the Sabbat of Lughnasadh, because this time of year was the time for trials.
Just as the Horned God is considered an amalgamation of so many male horned deities from many different pagan religions, so is the Triple Goddess so many female pagan deities rolled encompassed in one being. The Goddess is considered triple because she is thought to represent three stages of womanhood.
I read on one page an author describe the phenomenon as something like the Christian Father, Son, and Holy Spirit all being distinct, but all being One. Of course, Christianity and Wicca are not the same religion, perhaps that analogy can provide some sort of starting point from which those of us unfamiliar with Wicca may begin to understand just like those of us unfamiliar with piping wouldn’t jump right into a job at Hamilton plumbing.