Why does my Boyfriend keep freaking out, please help!?

Every so often my boyfriend of 10 months freaks out, and imagines that either, A) I dont love him anymore, B) He doesnt love me anymore or C) he thinks we are a bad couple (when we are a great couple). At the end of these little freak outs (which usually last about 5 hours) and are usually by text, he is ALWAYS fine, and ends up being extremely "lovey dovey" and smitten with me. However i always get so upset as i get terrified he is going to dump me :( he then gets annoyed at me for thinking he was gonna dump me as he always tells me he'll never leave me. Why does he get this mini little freak outs? is he maybe insecure? (He has always been a little insecure and has ALWAYS thought i'm too good for him) today he freaked out as i have decided to stay at home to go to university rather than move away. I didnt choose this just because of him but other things aswell and he freaked out as he doesnt want me to "regret it" incase we brake up. It just really upsets me :( i dunno why he gets like this...please help! also how could i help him? and how can i help myself cope in these situations and remember they are always alright in the end? thanks :)