whats happening to my dear friend?

i have this really close friend and we are always together. There's this one time that he stopped talking to us and would isolate himself while taking calls. None of us knew what happened to him or if he has problem or what. After a couple of days he texted me and he said sorry for not hanging out with us, he explain to me that he's been practicing balck magic and he is afraid that i might be affected by that ( since i am also practicing witchcraft and still a newbie ) after that i understood and just tell other teammates that he's been experiencing some family problems that's why he is kinda upset the past few days. After sometime he is back with his old self, joking around, being jolly again and so i thought everything was fine. Until one day he was not talking anymore, again i thought it was because of the craft he was practicing. But then as times passes by he would talk and make fun of my other teammates but not me. I didn't talked to him about this, i am not the type of person who would confront you if you all of a sudden doesn't want to talk to me anymore. Until now its still puzzling me, i don't know what happened. why do you think he acts like that? Before he practice the black magic he told me he might act different but he is still uncertain about that. Do you think this is the reason? Please share your idea..Thanks