Guy in uni has a problem with me and I can't figure out why. Any ideas?

To put a short story long, I started uni in september and made a few friends. There was one guy in lectures that I noticed was always on his own so I made an effort to speak to him and bring him into our group. It was clear that he didn't fit in very well as he didn't share our sense of humor and was also very PC and enjoyed discussing politics a lot which we weren't overly interested in. Eventually he stopped hanging out with us, and started dating this girl. I ended up developing an interest in the girl he was dating's best friend and I took her out on a date and it went really well. She mentioned it to him the following day and he told her that she should avoid me for her own safety. He then told her multiple lies about me for seemingly no reason.

1. He said he's known me for over 10 years (Nonsense, he met me in September)
2. He said I was heavy into weed and cocaine (Nonsense, only drugs I've ever touched are Weed and Shrooms and I haven't done either in almost 10 months)
3. He said I'm always in trouble with the police (Nonsense, don't even have a criminal record)
4. He said I used him at the start of uni to make friends and then turned all of his friends against him (Nonsense, I spoke to him at the start of uni because he didn't have any friends, he left our friend group of his own accord and as far as I'm aware, none of the others have a problem with him)

This girl has agreed to a second date with me and she mentioned it to him and he told her that she should get away from me now before I wind up hurting her. She asked what he means and he just said "You'll see." No idea what he means by this as I've never cheated on another girl or messed a girl around in my life, and every relationship I've had has always ended on good terms with no hard feelings between me or the ex.

Can't figure out why he's saying stuff. Tried confronting him but he refuses to speak to me. My friends are under the impression he likes this girl and is trying to screw things up for me as she is quite open about how she feels about me to her friends apparently. But like I said, he's dating her best friend, and I don't see any signs that he has any interest in the girl I like. I can't think what else it could be though. Any ideas?