the future

everytime he tells me "i want to be with you forever" or "i want us to get married and live together" i feel a bad because i dont really think of the same things ? i do love him but when i think of relationships i like to think of the present, not the future. And saying things like wanting to be together forever is a bit... this is my first relationship and i want to experience all types of people when it comes to dating... im only thirteen so i dont want to make any forever wishes in romantic relationships. its different for him since hes been in plenty relationships but i, on the other hand, have not. so i dont want to be pinned down to one relationship for the rest of my life . . . will he understand ? he seems pretty attached to me so i dont want his life to be in danger if i ever do truly  break up with him T_T