Oh, they were not temporary in days gone by! They were very much permanent.
Gerald Gardner incorporated a very old tradition into Wicca.
In old times only the rich were married (before Christianity),the less well off, rural peasants,held hands and jumped over the broom stick together. Here in Yorkshire, an unmarried couple living together are still said to be "living over the brush".
"Handfasting" is a memory of that old tradition. And a lovely ritual it is!