It's more about how Josy conducts herself. Not when you dump her, she's understandably hurt and angry there. But the attempted seduction when you're dating someone else, it just shows how far she's unfortunately fallen. And now that I think about it, Maya does something similar, but more subtle. Or rather, less blunt and obvious. She teases MC about his love for thigh-high socks, saying that she thought about him when putting them on, and if you're on her path that is exactly why she wears them. She even encourages him to feel it. Then there's the sexy whispering (peanut butter sandwich) that she explicitly said turns her on.
Both instances have the girls wear the same outfit no matter what, which makes me wonder if it was laziness on DPC's part to not bother rendering different clothes for different paths, kinda like if Josy wears your sweater or not, and wrote the scenes like this to justify the tempting clothes regardless of choice.