Ending a long term relationship advice please?

I am a senior in high school and have been dating my boyfriend for the past year. I am going away for college and he is not and we both know that we are not going to be together forever but still its hard...i thought that we would at least make it to the end of the summer but now im having doubts about even making it until the end of the school year. I could explain all the ups and downs of our relationship but that would take forever so the gist is we never had that much in common to begin with, as i have gotten to know him better i liked who he was before i got to really know him i guess because i saw him from a different perspective things are obviously not good if you are disliking someone the more you get to know them, i am at a point where i am having more fun hanging out with my friends than with him but to conflict with all of these obvious reasons we shouldn't stay together other than the fact the he smokes almost everyday and that has a bad impact on our relationship he is really a genuinely nice guy who repects me and treats me well. Hes not a bad guy and i perfectly enjoy his company i just think that i have settled or am just plain satisfied or content with where i am but am not particularly having the time of my life. We have already been extremely close to breaking up so this is sord of my second chance that i already gave him for things to get better and im at square one. We actually had a really great day today we went swimming and hung out and had some intimacy if you get what im saying and these thoughts are completely irrelevant to how i was feeling but then i had about a 2 hour talk with one of my best friends who knows both of us and its just to the point where im comfortable and could go on but whenever anyone asks my opinion about how i really feel about how my relationship is i always seem to come up with what i just told you and how we shouldnt really be together. Its hard because im really close with his family and even some of his extended family i know things like that shouldnt be the reason to stay in it but it does make it hard its a lifestyle that ive adjusted to. Im at the point where i dont need to break up with him and could at any moment but its not an emergency its just i want to do what i want to do as a senior in high school with my friends and not feel trapped or limited in terms of going on vacations with guy friends or anything like that because i have a boyfriend. im not lookign for another relationship and dont like anyone its just an evaluation. Im not really sure what im asking but more than opinions should i break up with him now even though its random and nothing is really wrong? what should i do? who else has been in my shoes? anything will help thank you