THE ONE??

so my best friend is a guy he's a senior. hes like my older brother I guess but when I started talking to my cousin bout him he's like lemme see some proof. so I showed him some screenshots and BAM...my cousin was like omfg he's the one girl u just wait for him. I don't know what to do about this? do I just pretend that he never said that or do I wait and see what happens with the guy?