This is the reason we do it.
This story is precisely the reason we continue the struggle for equality of rights for gay people.
Reports are that there was a string of escalating actions being taken against the couple, for no other reason that they are gay. The letter, followed by the vandalism, and the slashing of tires, were each escalations of the previous act. And it culminated in the arson attack that destroyed the home of these men. People could easily be killed in such attacks.