My girlfriend and I have been dating for 8 months now. I am 19 and she's 17. We both attend the same college. In one of her classes, she became close with the TA, who is 22. They exchanged numbers and talk regularly(skype, text, chat, call, etc). She talks to him much more so than she talks with me. She even texts him when I'm with her. They exchange gifts and meet each other often for coffee or to surprise each other at work. I have had past relationships that ended due to my partner's infidelity and I'm not comfortable with him being in the picture this much. I've voiced my concerns already. But to no avail. So my question is, am I being too overbearing? Or is she being insensitive of my feelings?

Does this guy know she has a boyfriend? She is being very disrespectful in my opinion. That is a bit much