Rooming

So my friend and I want to be roommates next year, but we are friends with his current roommate as well. His current roommate still wants to be roommates with him next year, but we already decided that we are going to live together. We could live in a triple, but neither of us want to do that. How do we tell him that we don’t want to live with him without being mean?

Can you come up with some excuse?
Like you wanted to be in the XYZ dorm, or closer to classes?
Or he is a night owl and you friend has to get up earlier?
Why didn’t he want to stick with him?

Way back in the day, I was the “current roommate” in this scenario. “You” in my case had the corner room; the “current roommate” wanted to move to the bigger room (or so he told me!). They just told me about the change, and no one had any problems.