1. Physical and emotional abuse
It is never okay for your partner to physically hurt you. I read in a bunch of articles that throwing things, or even slamming doors is considered physical abuse. Emotional abuse isn't taken very seriously, but if he is putting you down or name calling you, then it is time to walk out the door.
2. He makes no time/effort
A guy that likes you and wants a future will make time for you. Whether its an hour a day to eat together or even a phone call, he should want to hear your voice and see how you are doing. No exceptions.
3. Your intuition
That's right...if you feel like something is off and that you are not happy, do not put your feelings on the back burner. There is a reason you have doubts.