My girlfriend recently got her first job, and she got an assistant assigned to her who should keep an eye on newcomers and help them in every possible way, but this assistant turned out to be 27 years old and he was hitting on my girlfriend… He behaves very strangely towards my girlfriend, at first we thought that he treated everyone like that, but later we found out that he only treated her. For example: "You need to ask for help – Daddy help," whispers in her ear how well she's doing and that she's doing well, calls her baby, "If you want to hug, then I'm sitting here," "Come on, my chicks, go to lunch," holds out his hand so that she kisses him He called her to his place after work. He doesn't talk like that to all the girls, but only to mine, this manner of speech is far from just a joke and sarcasm. I hear all this from my girlfriend, and I'm sick of it, just like she is… We love each other very much, and even though I understand that she loves me just as much and won't trade me for anyone, I still get jealous, I don't know how right it is. I'm afraid that sooner or later my girlfriend will start to take it less seriously and stop seeing something strange in it and unknowingly start spending personal time with him. I'm 18 years old, my girlfriend is 19, and this guy is 27, so he also practiced boxing, I have his contact, but I'm afraid if I write to him, then my girlfriend will get even more attention. I do not know what is the right thing for me to do in this situation, and I ask for your advice and support. What is the best way for me to deal with this situation so that he gets behind her and I stop being jealous?
**tl;dr** I do not know how to maintain our relationship because of a man who is hitting on my girlfriend.