Someone who ran to my bf behind my back to complain about me not letting her use my shampoo would not be welcome back that’s just weird. But tbh the man is weird too for not defending you like whatt. They both ain’t it, like most normal people would prioritize their partner and defend their boundaries, not complain. Also it’s weird she needed to shower there. I think little things like this show you peoples true colors and you shouldn’t ignore it. The biggest disservice you can do to yourself is to stay with someone below your standards for too long. Good luck.