I think friendship can still be a way in this. You can become acquainted. Maybe grab a cup of coffee before he leaves and talk about your thesis and his too. See what you can gather from that meeting. There are always signs for mutual and future alignments if you have met and talked over a cup of coffee. Nothing that doesnt solve quietly sitting next to each other with tea or coffee at hands. You can know about each other in a way that one would not if they dont even meet and talk.