Most Helpful Guy
Sounds like he's afraid of what the relationship will be after you graduate. I'm assuming you'd be a lot further apart and long distance can take new strains on a (somewhat) new relationship. Maybe some insecurities led him to think he's holding you back... you should talk to him about the real reasoning, the least he could do is tell you why without making excuses.
Most Helpful Girl
He's letting his insecurities get the best of him, perhaps feels less that he's graduating after you and I don't know could affect his ego. Most of the time when sudden break ups happen theyre not thought of over night and h may have been thinking this for a couple of weeks and didn't know how to bring it up. He's making excuses also, I'd rather someone just say they didn't want to be with me, but I also think him not wanting the title says a lot more, how can he want to be with you but not want the titled, it's either you're together or your not, you can't go half assed. Sorry you're in this, best of luck x