The definition of marriage as understood and passed down to me by my parents, grandparents, great-grandparents...etc.,etc.,etc.
Other than "light", what defines sunshine?
Other than "harmony", what defines music?
Other than "truth", what defines honesty?
Other than "gravity", what holds the world in place?
What kind of a universe do you live in?
I can sympathize with that. But bear in mind all of our laws utlimately relate to the common good. Homosexuality is destructive to the common good.
For example, I don't want to live in a society where homosexuality is outlawed but neither do I want to live in one where I am forced to call it equal to heterosexuality.
In other words I can tolerate homosexuality just don't promote it or make me promote it.
One more thing.
Saying ,"...other than moral implications..." about something that affects family and society, is like saying what's wrong with jumping off a cliff "other than the abrupt stop at the end"