[drrotmos]

Or, rather than lying to the border agent (which I believe is a crime in the US, isn't it?), she could simply tell the truth: that she's visiting her husband and that she'll most likely be coerced to overstay her visa.

That should get her entry denied too.

[outworlder]

Precisely. Not sure if it is a crime or not (probably!), but lying is never a good idea, specially to an immigration agent.

Just telling the truth should suffice. The only issue is if it will cause trouble later on should she try to enter again. I assume it would.

EDIT: There is probably a 'alien will probably overstay' flag somewhere. Not a 'alien will overstay provided she is still married to an out of status alien'.