If he is sad because he is lonely?
And he doesn't speak the language well or drive well yet and he has not made new friends yet because he's new in the country?
Could trying to take some language/driving classes a possibility and making some new friends help? And see if the class is offered like... on a Saturday night?
Is the sad stemming from jealous? Could anything here help?
You can encourage and be supportive, but he's could own his own feelings, and then he could change his own behavior to hope to feel something new. Because if what he's doing right now on Saturdays is magnifying "sad and lonely" type feelings -- well.... change the behavior then. See if it feels better.
Does he have suggestions to offer for solving this himself when you talk to him? Or is he laying it all on you to solve?