The goal is for gay marriage to have the exact same legal protections that every other marriage has. No more, no less.
They can get that through civil unions, but choose to go after the term "marriage".
Good luck with that far left thinking of yours.
No, "they" can't.
Civil unions do not provide the exact same rights, benefits and protections that legal civil marriage provides.
Now, if you want to make ALL legal civil marriages into Civil Unions so those icky gays can't use the word "marriage" (although we've been marrying in churches for decades), go right ahead. That wouldn't put you afoul of the Constitution like your separate but equal idea does.