He says they're not important...?

one night i asked my boyfriend about is crushes coz i wanted to know mor about him and his past life. when i asked him how many girls he had liked or had crushed on, he told me only one which was the one he was in love with for four years. when i asked him about 'other' girls, he said there weren't any. i told him he was lying to me and that i knew there were more. he then told me that if there were, he didn't want to tell me because they weren't important to him. should i believe him?? or what should i think now?