Then why does the federal government ban bigamy? The 10th cannot abrogate the common law definition of marriage. It’s never been a state responsibilty to define marriage for itself.
If you had read Reynolds all the way through, they address your argument.
There is no federal criminal statute for bigamy. Yes, there are federal rules (administrative laws) that prohibit the federal government from recognizing plural marriages for the purposes of immigration. As I spelled out just above, since immigration is an activity that is left solely to the discretion of the federal government, there is no 10th Amendment issue at stake.
The last of the federal anti-polygamy statutes that applied to the states was repealed in the 1970s. It was called the Edmunds-Tucker Act. It's no longer "good law".
"If you had read Reynolds all the way through, they address your argument."
Yes, you keep saying that. I have read Reynolds now, twice. It doesn't say what you're asserting. Perhaps you'd like to share with us the passage of the opinion that you believe may be relevant. However, repeating "Just read the case", isn't going to cut it.
Furthermore, the concepts of "legal holding" and "obiter dicta" may be unfamiliar to you. In short, the legal holding in a Court opinion is the part of the opinion that addresses the legal questions set-forth in the case, and is the only part of the ruling that is binding on all lower Courts. I have previously indicated to you what the questions were in the Reynolds case. They weren't as you assert.