Boyfriend wants to watch me have sex with another man

Is that weird? I know some guys get off to that but I just can't even imagine sleeping with any guy but him. I don't think I'd even enjoy it and it wouldn't be fun to watch lol. I told him I'd never want to watch him do another girl And he said "well duh, we're different people babe. I know it's hard to understand but I just think it'd be hot". Have you ever done this or has your SO asked you to??