Confused about Boyfriend

So I am in a relationship with a guy that I really love but he is starting to get on my nerves. When we text our conversations can be going so great but then he just gets upset for no apparent reason. For example, I tell him that I love him then he says that I dont and that I'm just lying and that I don't want to be with him, or like last night, we were texting then he starts getting mad at me and asking me why I'm doing this to him.... I don't know what im doing to him! I apologize to him for no reason and he still doesn't accept my apology, i ask him to tell me whats wrong but he just tells me no, then all of a sudden he's fine and he tells me that he loves me. Someone tell me what to do about it. Im a freshman in college and this is really stressing me out!