I can't think of any reason why adults shouldn't be able to freely make such a contract. Some so-called conservatives would surrender the freedom to contract for a legal matter in the name of some notion of morality that no one is legally required to observe.
One doesn't have to like the free choices of others to be willing to protect the right of such choices.
It is a foot in the door and by giving into this immoral “contract,” they will keep working to open the door all the way and soon the definition of marriage being between one man and one woman will go down the drain. IMO it is everyone’s business who is interested in the cultural decline in which this sexuality force is taking us. They are powerful!!
Actually, anybody can enter sort of a “contract” that achieves the same thing.
Just give each other power of attorney.