[bossyTeacher]

I think it really depends. If you decide to smoke weed 24/7, I can choose not to be around you because I dislike drugs. Doesn't mean I was your friend before. You can replace "smoke weed" with joining a religious group (be it scientology, yehova witnesses etc), becoming a hiking junkie, only having a nighttime social life, joining a street gang, skating 24/7, going off-grid or some other time consuming thing that expects the other party to make things they might not want to do to be with you.

I became friends with you. If you change yourself by making a choice (whatever choice that might be), you shouldn't expect the other person to still stick with you.

[stevage]

I'm not quite sure what your point is. You can end a friendship with anyone for any reason. It usually takes more effort to keep it going than to end it.