His exact words were:
"I've been busy, and I hardly talk to you and I don't know, there's this feeling I can't express. Something deep inside me saying "let her go." The feeling that i like you as a younger sister. I've been thinking about it past few days. The night when you pranked me was our 7th month (Midnight of April Fool's; our 7th month was March 30th). It's alright to cry, to be angry, to be frustrated at me, it's ok to hate me. You might not be reading this right now, but when you do I'm really sorry. Like I said, I became irresponsible, so I decided to break up with you, so you won't be hurt. I'm doing this for you. Thank you for dating for 7 months, and I'm sorry for wasting that time. Think of this as the last letter from me. Again, thanks and sorry. Goodbye."
He's been distant past 2-3 weeks, barely talking to me... I don't know what to think. There were no other girls involved, so that's out. Wish he would explain more, but he won't talk to me.