My girlfriend is a hotel marketing manager, and her interpersonal relationship is very complicated. She said that she knew people from all walks of life. I always feel insecure.

This is normal. Especially the most popular people in the service industry. You should put your mind right. Now that she is in this position, she must have her own way and not suffer a lot. There is also that she is yours, and others can't take her away unless you are too jealous and take care of her, which will make her uncomfortable in the long run.