Advice on relationships?! especially if you have been in a long one?! 10 p?

hey so i met my bf a while ago. he liked me but i honestly did not like him at all. & i was also trying to get over someone else. he was a good friend to me in the process and out of nowhere i fell for him. its been really good for about 6 months..and then all of a sudden it got downhill. he doesnt text me or call me as much until i get mad about it..he said he wants time with his friends and all..but still he isnt the loving way he was before..and everytime i say i feel like he doesnt like me anmore, he gets mad and says he does. i believe him i do i know he appreciates me and likes me a lot. but idont know why this is happening. i heard after the 6th month or a while, the fights start happening and people get past it or either break up.. im gonna have a talk and tell him all that i feel such as he doesnt seem into it anymore. i miss the way it used to be. and im scared its gonna stay like this forever. maybe im just being paranoid and we just got to a point where we are comfortable..idono any thoughts or suggestions or assumptions?