We have kinda been here before with civil partnerships.

In Scotland, a civil partnership is MORE binding than a marriage. Adultery is grounds for divorce but it is NOT grounds for dissolving a civil partnership. Too late to look this up now, but I suspect absence of solatium (Scots-law concept resembling "consummation") doesn't feature as a ground for breakup of a civil partnership either.

We don't have gay marriage here yet. It seems odd that it would imply *looser* standards than the arrangements gays can make at present, but if that's the way the family moralists want it...