My best friend's acting cold n indifferent?

this guy n i have been best friends for the past 3 years.. n a year back, i discovered that i'd fallen for him.. soon after that, he went to a different country for his further studies.. but we maintained proper contact n things were really going fine.. untill 4 days back when he saw pictures of his ex n told me he was missin her.. n i got really sad.. d very next day v had a huge fight.. i agree he hasnt been into any commitment wimme.. but now he is badly irritated wimme n hasnt spoken to me properly since that conversation.. i jus cant be with him behaving so indifferent n cold wimme.. what should i do? PLEASE help!! :(