0:26 here we can see that at this moment J.Seph is looking up while Bm was focused on JiWoo and looking down... to a specific region... Let's be honest, Matthew Kim is a grown man and can certainly "appreciate" his girl, but he doesn't even try to disguise the desire!
When bm interact with jiwoo , jseph got jealous and when jseph interact with jiwoo, bm got jealous.. Ok now we can conclude that both bm and jseph have feeling toward jiwoo..but jiwoo just treat them as her older brothers😅😅😂