~”Smith had sex with wives of other men. That is adultery under any standard; not just polygamy.”~
Smith was -sealed- to wives of other men. (And it is fundamental to this discussion to understand the difference between sealing and marriage.) It’s not clear to me as to why; but there were purely dynastic arrangements made in some cases. Whether or not there was sexual intimacy between Smith and wives of other men is not substantiated by reliable evidence. We have a few secondhand accounts and claims, but no more.
The question then becomes, if there is no sexual intimacy in the relationship, is it adultery?
It's very ckear to me. When smith was caught screwing the wives of other men, he had to come uo with some excuse. It's really pretty simple.
The answer is:
Matthew 5:27-28
27. "You have heard that it was said, `Do not commit adultery.'
28. But I tell you that anyone who looks at a woman lustfully has already committed adultery with her in his heart.