"I certainly hope you're not going to Los Angeles to hook up with your boyfriend. That would be incredibly disrespectful to our family while we're still married."
Let her respond.
If she denies it, say "I hope you're telling me the truth, and I will know if you are." If she admits to it, say "Thank you for being honest with me -- that gives me clarity as to what I must do while you are gone."
And then say nothing further.
Now of course, you don't have to do ANYTHING while she's gone, but the ominous statement will at least ruin her good time!!
