Is that what the whole issue is about? Its like the hotel room where you pay $65.00 for one occupant and $75.00 for two occupants??
If thats all that we are worrying about, I wojuld say that Civil Unions are proper no matter whom is involved in the contract, but that perhaps the law should state that there can only be one other person involved in a civil union at any one time.
That way, should you ever later want your fancy Catholic Wedding,
You can still have it---but your buddy won't get cheaper insurance any longer unless you marry him. That privilege is now for your wife.
(assuming Catholics ever allow gay weddings to begin with)
I think I see your point, though:
Civil Unions are business contracts.
Gay Marriage goes deeper. It is a social statement.
Even as a Christian, I see nothing wrong with allowing same sex marriage legislation. If we simply allowed it and quit trying to judge people, the controversy would vanish.
Let God judge the intents and purposes of the heart. Love your neighbor and stay out of their business.