An important reminder that abuse can sometimes be very subtle. This list is from a Huffpost article, Identifying the more subtle signs of an abusive relationship:
The guy who barricades a door so that you cannot leave a room during an argument until you have given him his "rightful" opportunity to talk circles around an issue he created is the guy who needs to control your physical space. This is a guy who is used to being given opportunities to talk his way out of situations. If it happens once, shame on him. If it happens twice, shame on you.
The guy who does not leave your dorm/apartment/home when you've asked him to is the guy who does not respect your boundaries, your physical space, or you. Likewise, the guy who shows up to your home when you have explicitly asked him not to is the guy who does not respect your boundaries, your physical space, or you. None of this is cute; none of this is endearing. It is offensive and an abuse of your boundaries.
The guy who is not honest about who his friends are has something to hide. There is absolutely no two ways about it.
The guy who goes out of his way to say and do things that annoy you is worse than a child; this is a guy with clear control issues -- he needs to know that he can manipulate you successfully, and this is one small way to test it. None of this is cute; none of this is endearing.
The guy who says nasty and hurtful things about your major/career in a way that you know goes beyond innocent teasing is the guy who is deeply uncomfortable with his own life choices. I would not touch those issues with a ten foot pole.
Have you ever apologized for your "role" in his behavior? This is Master Manipulation, at its finest. Not only has he behaved poorly, but he has found a way to manipulate you into believing that his behavior is/was/and will continue to be your fault. This issue is particularly difficult to pinpoint. Figure it out, and as soon as you do, run.
Do your friends give you "the look" when you share details about the most recent argument? This is a subtle, yet helpful clue that your repertoire of problematic relationship issues is reaching its quota.