If you are in a commited relationship, that does not mean you stop finding other people attractive. It means you are making (it is a constant thing you have to do) a conscious decision to NOT act on those attractions becuase your partner is someone you are committed to.
But you have to (in my opinion) be very honest with yourself. Don't try to fool yourself. Be homest with yourself and with him. If you are not, then things can get messy.
good luck!
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