Girlfriend is harassed every day. What should I do? What should I do to harass my girlfriend or colleagues? Ask big brother and big sister for help, thank you?

First of all, start with colleagues, treat him better than usual, and invite him to dinner or something. And intentionally or unintentionally mention the topic about your girlfriend, it is best to get something about your girlfriend from him and understand his attitude towards your girlfriend. Then persuade him as a bystander and guide him slowly. Then there is your girlfriend. Let her relax at work and try to go with other colleagues. This is a safer method. Actually, you're right. Why not just tell him? What's more, don't fight poison with poison. Behavior, attitude and language should not be too radical, which will make him have extreme psychology.