[PatrickHenry]

If Utah decided to recognize bigamous marriages, I doubt very much that Virginia would honor them.

Isn't that why Utah had to give up the legality of such marriages as a precondition of statehood? I'm not certain of this, but I'm "fairly" certain.

[f.Christian]

snatch clone new sociopolitical world order super statist worshiper placemaker !

[CobaltBlue]

I think Congress was opposed to Utah becoming a state due to the bigamy issues.

As to whether there was a fear that the rest of the states would have to recognize polygamous marriages, I just don't know.

The SCOTUS hasn't taken much interest in divorce cases in many years, so for the most part the most powerful arguments are from state courts these days.

I think it's completely unheard of for Congress to take an interest in marriage, much less elevate it to constitutional status.