I didn't see other leaders spouses either. Why would she go there for an overnight? It's snowy, the are many snobs and plastic politicians and she left Europe for a reason why go back on a a short business trip.
As an aside, I'm glad to see Wilbur Ross there, the guy is quite simply an old crafty honorable beast who works hard for Trump. To me he just gives off that air of someone who is loyal and patriotic, who could have $10 in his wallet or millions in his bank account and it makes little difference in his persona. As long as he is by his side, I have faith in Trump putting America first economically. I've followed closely the NAFTA negotiations, and Wilbur is as badass as any. Never pulling punches and not allowing the wool to be pulled over his eyes.