Whats going on ?

yesterday ,i made a friend from Denmark and we had a nice talk .He ever said be friend should be believe each other and no lying .Thats true and also made me feel its so nice and easy to make friend with foreigners.Thats yesterday .But today ,there was something wrong with us .Now he is mad with me .First, before dinner I told him we talked one hour later .But I had something to do and forgot the time .Also he went out.But he left message to me .Second when he talked with me on msn ,my sister was calling .I need to answer her and the net had to cut off .After that ,he said I dont respect our friendship and asked me to delete him ,dont talk to him anymore .He is so angry .I want to explain ,but seems helpless .thats make me upset and strange .Why ?I really dont want to botch our friendship .I said sorry for many times .I dont know what should I do .Is that the different culture between us ?or what anything else ?I dont want to lost friend that I just made .I do want to cherish our friendship .Hope what i wish ~!