I been in a relationshipd for almost 6 years, on and off.?

there were other guys, but they were . The guy im with, A, has lost my trust in the past over something that meant a lot to me. I left him at that point, until he came back to me. I made him apologize and made him realize what he did. Anyhow, I do love him. He loves me and wants to marry me. I have been fighting with him a lot, lately and he called my best friend and told her not to tell me because he doesnt want me to get mad ( that he called her) I doubt him, and I am afraid of geting hurt again. I am not able to fully trust his words. He has never cheated on me, his lies are more the type " ill do this, and that- but doesnt get it done". I feel I am more mature then him. I think that his mistakes were done throuth immaturity, however, I dont understand how a man (23 years old) can be so stupid. Am I too smart to be wth him? I dont feel the spark with him anymore, the thing is, i do love him and been throgh a lot with him. I dont want to leave him, again, yet if I do leave him this time theres no going back. I am afraid I wont find someone else. I dont feel im physicaly. or mentaly attracted to him. I feel as if he is to slow for me. I am independant and he is not.I am willin to givre him time to grow. but is growing goin to change him? He is startin to mature and become a bit more independant. He loves me, and always tells me that he values me and that I am someone he doesnt want to lose. I dont know if this is permanent or after a few years he will be uninterested in me. I dont want to break up totally with him because I dont know if I will ever be able to forget him. If i doo find the PERFECT guy in my eyes, will I thn forget him?I am confused. and I feel that I am leading him on, but i dont want to lose him, yet i am not sure if i want to deal with these issus with him, but i realized that everyguy will hve some type of differences, no one is perfect...