You aren't being stupid. You are recognizing that you aren't happy. It sounds like you are just two different people who want different things. It doesn't mean that you are being hateful. You just have begun to develop different personalities and this has led to unhappiness on both sides. If you continue to try to involve him and you spend less and less time together you could become more resentful. You got together young and you missed out on a lot. You could be feeling that now. You don't have to be with someone because you started young and you should never be with someone out of obligation. Decide what you want and execute it. If you don't want this anymore then end it. If you are not compatible then end it. It's not stupid to want to be happy.
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