Why does my bulgogi marinade turn out watery?

Hi everyone, I've been trying to recreate the bulgogi I saw in a Korean drama for my family's big weekend dinner since we all got hooked after watching it together. I used soy sauce, sugar, pear juice and garlic like the recipe said, but after marinating overnight the sauce became super watery and didn't coat the beef nicely when I cooked it. My kids still loved it but I want that nice glossy sticky look next time, hehe. Do I need to reduce the sauce separately first or maybe add less pear juice? Any tips would mean so much, thank you in advance po!