I don't understand his motivation?

Okay so I've been seeing this guy for a few months. We both agree that a relationship was not right for us when we started to see each other, because he was still living with his ex. He claimed she was living with her sister until she/he could moved out. This bothered me so I told him maybe we can further our relationship once things got more figured. So we remain friends and helped through something major that happened to me about a month. I started to like him more and more we hanged out with each other. We became intimate (Even though I knew it was wrong, but he claimed he was not with his ex) I asked what we wanted of our relationship, and he told me he still not ready for a relationship so I decided cut ties with him. I figured it would be best before I got even more attached with him. But even if we talk at work he constantly ask me if I'm talking to anyone else. His attitude towards me has done a 180. I'm might be living the job next week, so I will not have to deal with him anymore. He told me he wants to remain friends, but I don't think that will work. I don't know why he constantly asking who I'm talking or seeing. But if I mention his ex he is like it's none of your business now that we are just friends.

?2014-03-22T22:27:53Z

He's having a hard time letting go of you.

He's also having a hard time letting go of his ex.

Move on. You don't need that.