could he forget me so easily?

Dont even know where to start. First time i saw my ex i thought he was gorgeous. And within weeks of first meeting we both openly flirted with each other however, i knew he wasnt interested. Everyone at college thought we were a couple and i kinda think that fueled my liking towards him. Anyways his female best friend became a very close friend of mine and from her i found out that he was interested in me. Anyways after 4 months of me completely lusting after him, i made the first move. I was confident as i found out from many sources that i was exactly his type. PLUS we had been texting everyday allday. We started dating in january and he told me he loved me. Spoke from the minute we woke up to the minute we went to bed. 2 months later we slept together. Everything was amazing until around May. Exams started, everyone was stressed. He started replying less and less. Which is understandable. As exam season progressed he started payin next to no attention to me. And always put it down to exam stress and lack of sleep. So i left him to it. Which was hard. But i didnt want to pressure him on top of everything else. Anyways. Exam period finishes and i hoped everything would go back to normal. But he had become so distant that i barely knew him. He would laugh and speak to everyone but me. I confronted him about it and he apologised. We had sex (sorry if tmi) and 2 days later he told me that he had lost all feelings for me. He seemed extremely apologetic and stressed how he tried to keep everything going but just couldnt feel anything towards me. This almost destroyed me. I felt used and discarded. But i wanted him to be happy. If thats without me then so be it. Thts what love is right? The part that kills me the most is that now he doesnt even look at me. He ignores what i say. Doesnt even try to be friends. I swallowed my pride and made smalltalk bout a football game and he told me that i should just drop it as he doesnt keep any connections at all with girls that he has dated. Its awkward as we have the same circle of friends. I just dont understand. How can he go from loving me and telling me every little secret of his to acting like ive never existed? All within a matter of a few weeks. I know for sure there isnt another girl in the picture because he has been cheated on before and claims would never put anyone through what happened to him. I just dont get it. How can someone just lose interest like that?