How do I handle: 2 players want same game, but won't play with each other?

[Zelligars Apprentice]

Wow. Looks like I tapped a vein here.

Thank you all for your responses. You have given me a lot to think about.

 

[Silver Moon]

Just to add to the discussion, I will ask: Has anyone ever actually been in this situation? If so, how did you handle it?

Yep, in a Play-by-Post game that I ran. It was resolved by one player taking a break, then coming back in a way that their charcters did not have to directly interact. It was a bit tricky for both myself and some of the other players but we got through it and the module ended rather well for everybody.