How Relevant is the Past?

Just how relevant is the past? What I have learned is that sometimes the smallest thing done to you in the past, can still affect you. Whereas some big things you’ve done to someone else, you don’t even remember. I was confronted by an old grammar school classmate, on MySpace, and he told me about all these occasions that I teased him. I could vaguely remember one of those incidents. But, I thought to myself, wow, what a loser. For him to even remember that stuff MUST mean he doesn’t have a life. Then, I ran across a girl on Face book; a girl who had infuriated me on like three occasions in 8th and 9th grade. And when I saw her on mutual friend’s page, I went wild. I called her every bad word I could think of. And she asked me “where is all this coming from”? I broke down every incident to her, and she could barely remember any one of the incidents.
I thought of this analogy when talking to my boyfriend today. There are things from the past that he has said and done and not said and done. Some things I mentioned to him, other things I did not. But today was one of those days. I had so many questions as to his reasoning. He had behaved in ways that I did not understand so many times in the past, that I wasn’t sure of how he felt about me in the present. And he kept saying he didn’t remember the incidents when he didn’t return my call or my text. And when he did remember something, he didn’t remember why things went that particular way. I find myself trying to not let things from over a year ago plague me today. But I can’t help it. I can’t help but feel, that because of his nonchalant and un at tentative behavior towards me in the past that he doesn’t really care for me. Or that he didn’t like me, but because I “kept hanging around”; he eventually said what the heck. I can’t help but feel that way. He called me four times today. He listens to me nag regularly. He’s not good at expressing his emotions, but he tries. He’s sits on the phone with me till 4am three to four times a week, just because I want to talk. But despite his CURRENT behavior, I cannot stop thinking about all the times he didn’t call, he didn’t text, and I felt like he didn’t care. So what can I do?
Can I force myself to forget what is so vivid in my mind? Is it so vivid because it’s relevant? Am I over reacting? Is he under reacting? Every time I dig into the past, I hit a brick wall. He’s unreceptive to the conversation. He just says sorry, but what I want is an explanation. Was he seeing somebody else back then, and it didn’t work out? How else could a man go from being COMPLETELY nonchalant about a woman, to not wanting to be without her, in the span of two years (when he spent the first year and a half kind of being a jerk).
This blog doesn’t have a conclusion. I am looking for one.