Why would a guy say on the phone “if you hook up with a guy I want you to be honest with me” when I told him I got invited to a guy’s party?

And then he goes “im going to let you go now because I might say something stupid” why did he get irritated? We are just friends

Why would a guy say on the phone “if you hook up with a guy I want you to be honest with me” when I told him I got invited to a guy’s party?
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