No wonder you're upset, Joyce. That sounds extremely distressing! It's not like this is some guy you barely know who is suddenly acting all weird around you; it's a guy you have been tight with for four years. If the only thing different about him was the way he was acting toward you, we might think he was (lamely) trying to break up with you, without having the guts to say it to your face. But you also said he's stopped caring about his grades and is just acting strange in general, which makes us wonder if he might be going through a bad time and maybe depressed. Have you tried talking to him directly? What does he say? Whatever is going on with you, he shouldn't treat you badly, or make you cry because you're upset by his actions. You certainly want to stick by someone if they are going through a rough time, but not at the expense of your own happiness. If, after speaking with him, you're still confused and not getting a straight answer, you may need to let him know that you want to be with him, but not if he's going to be unkind. Either he'll see that he's being hurtful and get his act together (or, if he's depressed, maybe go and get the help he needs) or he won't, and then you may have to make some tough choices of your own, like walking away from this relationship. Good luck!

—Andrea Pyros