This happens on a reguarly basis, I fight with my friend because he is always changing certain perspectives of his attitudes, and when I engage somehow in regards to one of these perspectives they get upset with me and I end up looking like the a**hole for getting angry with they're reaction. Is it normal for me to get angry with this?

So just don't rise to the bait. Next time they arbitraily change their position on some topic just say "that's nice."