Why would a guy apologize for being distant ?

This guy I've been dating has been really busy lately and hasn't really been keeping in contact with me or responding to me when I email or call him. I know he really likes me, but my trust issues won't let me accept it, out of the blue, he emailed me and said he really does apologize and that he's sorry and what not. But why ? I never complained about it ?
Why would a guy apologize for being distant ?
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