To me it sounds like he thinks that getting excited about going to college just makes it one step closer to leaving behind all he has known and loved for the past 18 years.
Senior year can be so exciting with all of the “senior only” events at school. You’re at the top of the world! He probably has a solid group of friends that are hearing from schools as well and guess what, many of them may go on to different colleges. Kind of hard to be excited when you realize that your best buds won’t be with you everyday anymore. Plus, you’re gonna be at the bottom of the heap once again, as a freshman.
Heart to heart, respected adult side bar discussion…may not be that deep. Giving him some personal space while he comes to term with this new chapter in his life, while being available as a sounding board, may work for him.
Just my opinion, yours may differ.